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.     

Do different implant surfaces exposed in the oral cavity of humans show different biofilm compositions and activities?

Osseointegrated dental implants play an important role in restorative dentistry. However, plaque accumulation may cause inflammatory reactions around the implants, sometimes leading to implant failure. In this in vivo study the influence of two physical hard coatings on bacterial adhesion was examined in comparison with a pure titanium surface. Thin glass sheets coated with titanium nitride (TiN), zirconium nitride (ZrN) or pure titanium were mounted on removable intraoral splints in two adults. After 60 h of intraoral exposure, the biofilms were analyzed to determine the number of bacteria, the types of bacteria [by applying single-strand conformation polymorphism (SSCP analysis) of 16S rRNA genes], and whether or not the bacteria were active (by SSCP analysis of 16S rRNA). The results showed that bacterial cell counts were higher on the pure titanium-coated glass sheets than on the glass sheets coated with TiN or ZrN. The lowest number of bacterial cells was present on theZrN-coated glass. However, the metabolic activity (RNA fingerprints) of bacteria on TiN- and ZrN-coated glass sheets seemed to be lower than the activity of bacteria on the titanium-coated surfaces, whereas SSCP fingerprints based on 16S rDNA revealed that the major 16S bands are common to all of the fingerprints, independently of the surface coating.     

Modified implant surfaces show different biofilm compositions under in vivo conditions

Objective: Plaque accumulation on implant surfaces can result in peri-implantitis with potential implant loss. The aim of the present study was to examine the influence of zirconium nitride (ZrN) as a potential implant surface on the biofilm composition and diversity in vivo .
Material and methods: ZrN- or titanium (Ti)-coated glass specimens and ZrN or roughened Ti discs were used as substrates. Pure glass and polished titanium served as controls. The specimens were mounted on removable intraoral splints in five adults. After 24 h of intraoral exposure, the biofilms were analyzed applying single-strand conformation polymorphism (SSCP analysis) of 16S rRNA genes. Sequence analysis of the dominant bands excised from the SSCP fingerprints allowed to taxonomically describe bacteria derived from biofilm samples.
Results: The highest number of bands was counted on pure glass and Ti 800. ZrN-coated glass and ZrN-coated titanium discs showed the lowest values for species richness. However, no significant differences were observed regarding the diversity of the identified bacterial species among all the surfaces examined. A total of 46 different bacteria were identified. The dominant bands within the fingerprints indicated bacteria belonging to the Streptococcus group as identified by their 16S rDNA sequence.
Conclusion: A coating of glass surfaces with ZrN significantly reduced the species richness in early bacterial colonization but the diversity was not significantly changed. In consideration of the results obtained by this and former studies a ZrN coating appears to rather modify the quantity of early bacterial adherence than the quality of the microbial community structure.     

种植体穿龈部分氮化钛纳米涂层对牙龈成纤维细胞粘附和增殖的影响

目的:明确氮化钛纳米(TiN)涂层对人牙龈成纤维细胞(HGF)粘附形态和增殖的影响, 作为选择合适的种植体穿龈部分涂层的依据之一。方法:利用磁控溅射技术制作氮化钛(TiN)和对照Ti涂层,测量各组材料表面形貌、元素含量、粗糙度和亲水性,原代培养人牙龈成纤维细胞(HGF),通过扫描电镜SEM和CCK-8观察分析不同纳米涂层上方细胞粘附和增殖差异。结果:TiN组表面HGF粘附形态与Ti组相似,而HGF增殖幅度大于对照Ti。结论:本实验所设计的氮化钛(TiN)涂层利于促进HGF增殖,推荐作为种植体穿龈部分涂层。     

Focal adhesion formation of primary human gingival fibroblast on hydrothermally and in-sol-made TiO2-coated titanium

Optimal cell adhesion of the gingival fibroblasts to dental implants is important for maintaining good implant integration. The aim of this study was to discover, if the nanoporous TiO₂-coating on titanium alloy substrates is able to increase the cell adhesion of the human gingival fibroblasts (HGF). The study consisted of three differently produced titanium groups: hydrothermally produced TiO₂-coating (HT), novel TiO₂-coating made in sol (SOL), and noncoated control group. Primary HGF cells were initiated from gingival biopsies from patients having a third molar extraction. HGF were cultivated on titanium discs for 2 and 24 h to determine the initial attachment with confocal microscope. The cell spreading and adhesion protein signals were measured. In addition, expression of adhesion proteins vinculin, paxillin, and focal adhesion kinase (FAK) were measured after 3 days of cultivation by using Western Blotting. Higher protein levels of paxillin, vinculin, and FAK were induced on both coated discs compared to noncoated discs. The difference was statistically significant (p < 0.05) concerning expression of paxillin. The cell spreading was significantly larger on SOL discs after 2 and 24 h when comparing to noncoated controls. The confocal microscope analyses revealed significantly higher adhesion protein signals on both HT- and SOL-coated titanium compared to control group. This study showed, that both methods to produce TiO₂-coatings are able to increase HGF adhesion protein expression and cell spreading on titanium surface. Accordingly, the coatings can potentially improve the gingival attachment to titanium implant surfaces.     

Effect of laser-dimpled titanium surfaces on attachment of epithelial-like cells and fibroblasts

PURPOSE

The objective of this study was to conduct an in vitro comparative evaluation of polished and laserdimpled titanium (Ti) surfaces to determine whether either surface has an advantage in promoting the attachment of epithelial-like cells and fibroblast to Ti.

MATERIALS AND METHODS

Forty-eight coin-shaped samples of commercially pure, grade 4 Ti plates were used in this study. These discs were cleaned to a surface roughness (Ra: roughness centerline average) of 180 nm by polishing and were divided into three groups: SM (n=16) had no dimples and served as the control, SM15 (n=16) had 5-µm dimples at 10-µm intervals, and SM30 (n=16) had 5-µm dimples at 25-µm intervals in a 2 × 4 mm² area at the center of the disc. Human gingival squamous cell carcinoma cells (YD-38) and human lung fibroblasts (MRC-5) were cultured and used in cell proliferation assays, adhesion assays, immunofluorescent staining of adhesion proteins, and morphological analysis by SEM. The data were analyzed statistically to determine the significance of differences.

RESULTS

The adhesion strength of epithelial cells was higher on Ti surfaces with 5-µm laser dimples than on polished Ti surfaces, while the adhesion of fibroblasts was not significantly changed by laser treatment of implant surfaces. However, epithelial cells and fibroblasts around the laser dimples appeared larger and showed increased expression of adhesion proteins.

CONCLUSION

These findings demonstrate that laser dimpling may contribute to improving the periimplant soft tissue barrier. This study provided helpful information for developing the transmucosal surface of the abutment.     

Microbial community composition on modified dental implant surfaces: an in vivo study

Purpose: The aim of the present in vivo study was to examine alterations of the microbial community structure in biofilms on different dental implant surfaces over the time. Materials and Methods: Zirconium nitride-coated glass (ZrN-glass) and ZrN-coated polished titanium (ZrN-Ti) disks were used as substrates and polished titanium (Ti-pol) was used as a control. The specimens were mounted on removable intraoral splints in one adult. After 24 hours and 14 days of intraoral exposure, the microbial biofilms were analyzed by generating 16S rRNA gene clone libraries. Results: ZrN coating of a Ti surface altered the microbial composition early on (24 hours), with a tendency to augment Lactobacillus-related phylotypes later. Long-term exposure (14 days) of dental implant surfaces to microbes resulted in a significantly different composition of the biofilm on all three tested surfaces. Conclusions: This preliminary study showed that a ZrN-Ti disk surface harbors a significantly different microbial composition from a polished Ti surface. Further improvement of ZrN physical vapor deposition coatings might help to influence the adhesion of bacteria that are less pathogenic, thereby reducing the risk of peri-implantitis.     

不同钛表面形貌对人牙龈成纤维细胞生物学行为的影响

目的:良好的种植体颈部软组织封闭是种植体远期成功的重要因素之一。生物封闭的的主要决定因素之一是种植体颈部的表面形貌。本实验的目的是通过比较三种不同的纯钛表面形貌结构对人牙龈成纤维细胞的生物学行为的影响,寻找一种有利于牙龈胶原纤维附着的较理想的种植体颈部表面形貌,为种植体颈部设计提供指导。方法:本研究采用机械加工处理、电化学腐蚀、电化学腐蚀加酸蚀的方法在纯钛金属表面形成三组不同的表面形貌结构;用激光共聚焦显微镜检测其表面粗糙度;扫描电镜观察其表面微观形态并用X射线能谱色散谱仪检测其表面成分;将其与人牙龈成纤维细胞共同培养,MTT法检测表面细胞的增殖情况;细胞计数仪进行表面细胞计数;扫描电镜观察表面细胞的形状及排列。结果:机械加工组表面较光滑,呈浅的等向排列的微沟纹,表面粗糙度Sa为0.8783±0.2578μm;电化学腐蚀组表面略粗糙,呈圆形或椭圆形浅碟状凹,直径约10～15μm,分布均匀,凹内含有散在的小孔,小孔的直径约为1-5μm,表面粗糙度Sa为1.7530±0.3711μm;电化学腐蚀加酸蚀组表面略粗糙,呈圆形或椭圆形浅碟状凹,直径约10～15μm,分布均匀,凹内含有散在的小孔,小孔的直径约为1-5μm,表面见均匀的半球形纳米突起形成,直径约50～100nm,表面粗糙度Sa为1.6763±0.3440μm。表面成分检测显示三组均未有任何污染物在钛表面。牙龈成纤维细胞在各组钛片表面生长良好,形态正常,各组钛片对于细胞没有明显的毒性,生长曲线与正常细胞的生长曲线规律一致。机械加工组表面细胞沿着材料表面微沟纹平行排列,细胞扁平,伸展较差,细胞伸出的伪足较短;电化学腐蚀组表面细胞自由分布,细胞丰满,伸展良好,细胞伸出的伪足较长,有的伪足伸入到邻近凹内;电化学腐蚀加酸蚀组表面细胞丰满,伸展良好,伸出大量伪足,伪足很长,呈细丝状或带状,可伸入到相隔较远的凹孔内,呈悬空样,也可相互交织成网状。结论:电化学腐蚀加酸蚀可在纯钛表面形成均匀分布的直径为10-20μm的凹及直径为1-5μm的孔,凹及孔的表面均匀布满了直径为50-100nm的半球状突起。电化学腐蚀加酸蚀表面促成纤维细胞粘附作用最强。本实验中形成的微米凹、孔形态及半球形纳米形态均有利于成纤维细胞的粘附。电化学腐蚀加酸蚀方法形成的表面是一种较为理想的种植体颈部表面,可以为种植体颈部设计提供指导。     

Initial attachment of human gingival fibroblast‐like cells in vitro to titanium surfaces oretreated with saliva and serum

Wound healing at the implant‐soft tissue interface occurs in the presence of saliva and blood. The aim of this in vitro study was to investigate potential influence of saliva and serum on initial attachment of human gingival fibroblast‐like cells to titanium (Ti) surfaces. 10×10mm large specimens were prepared from pure Ti, incubated for 1 h in either whole human saliva, fetal calf serum, their mixtures in proportions 75:25, 50:50 and 25:75, or buffer as control. Subsequently suspensions of human gingival fibroblast‐like cells were applied in 4 separate assays to Ti surfaces for 40 min and cell attachment was evaluated by means of image analysis under reflected light microscopy. Significantly lower numbers of attached cells ( p <0.001) were found on all surfaces pretreated with saliva alone or in combination with serum. Pretreatment with serum alone showed no consistent enhancing effect on cell adhesion. These results suggest that exposure of implant necks to saliva during implant insertion or peri‐implantitis treatment might inhibit adhesion of gingival fibroblasts and thus indirectly support isolation of the implant by epithelial proliferation.     

Removal of HA and TPS implant coatings and fibroblast attachment on exposed surfaces

The removal of implant coatings may be necessary if rough implant surfaces are exposed subgingivally due to progressive peri-implant bone loss or if they are also supragingivally exposed because of progressive gingival recession, thus facilitating plaque formation and impairing tooth cleaning done at home. The aim of this experimental study was to develop diamond-coated files and rubberized polishers for machine-driven instrumentation of implant cylinders, and present an instrumentation concept for the complete removal of rough titanium plasma spray (TPS) and hydroxylapatite (HA) layers and polishing exposed titanium surfaces. The surface structure and its possible contamination by the instrumentation process was investigated using laser profilometry, scanning electron microscopy, and x-ray fluorescence analysis. The effect of impurities on the growth of human fibroblasts was tested in cell culture. The results show that TPS and HA implant coatings can be removed with the modified implant files. After polishing the exposed titanium surfaces, roughness depths of Rz=4.6 microm (TPS) and Rz=5.7 microm (HA) and, for implant cylinders, 3.4 microm were found. During the instrumentation of implant surfaces, contamination with the material of the instrument must be expected. It was shown that, in principle, growth of human gingival fibroblasts on the instrumented surfaces is possible. The cells were intimately associated with one another and, compared to culture controls, demonstrated good adhesion with strict orientation to the microstructure of the scoring left by instrumentation. The biological consequences and mechanisms of cell adhesion on instrumented surfaces require further investigation.     

Human gingival fibroblast functions are stimulated by oxidized nano-structured titanium surfaces

Objectives

The aim of this study was to analyze the features of an oxidized titanium implant surface and to evaluate its effects on the response of human gingival fibroblasts.

Methods

10 mm × 10 mm × 1 mm turned (control) and oxidized (test) titanium samples (P.H.I. s.r.l., Italy) were examined by scanning electron microscopy and atomic force microscopy and characterized by height, spatial and hybrid roughness parameters. Primary cultures of human gingival fibroblasts were seeded on titanium samples, and cell morphology, adhesion, proliferation and extracellular matrix deposition, in terms of type I collagen synthesis, were evaluated.

Results

Control and test surfaces appeared considerably different at the microscopic analyses: turned samples were grooved, whereas oxidized surfaces showed a more complex micro- and nano-scaled texture, as evidenced by roughness parameters. Cell adhesion and proliferation rate, as well as collagen synthesis, were greater on oxidized vs turned surfaces.

Conclusions

Although both control and test samples were in the range of average roughness proper of smooth surfaces, they exhibited significantly different topographic properties in terms of height and, mostly, hybrid parameters. Furthermore, oxidized surfaces enhanced human gingival fibroblast adhesion, proliferation and extracellular matrix deposition, and this could be due to the different structure at micro- and nano-scale levels.

Clinical significance

Oxidized nanostructured titanium surfaces could have a significant clinical utilization in virtue of their affinity for soft tissue attachment at the implant neck and/or at the transmucosal portion of the prosthetic abutment.     

Migration, attachment, and orientation of human gingival fibroblasts to root slices, naked and porous-surfaced titanium alloy discs, and Zircalloy 2 discs in vitro

Cell migration, attachment, and orientation of cultured human gingival fibroblasts (HGF) were measured in relation to four types of specimens: Ti-6Al-4V alloy discs with either ground surfaces or porous structured surfaces, and Zr alloy discs (Zircalloy 2) with either ground surfaces or surfaces modified by being heated to form a thicker oxide cover. Surface-demineralized and non-demineralized root slices were used as controls. Initial cell attachment was measured by means of a 51Cr assay, and cell attachment and orientation following migration by an assay that measures development of the resulting refractile material in relation to the specimen. No significant difference between initial cell attachment to Ti alloy and control demineralized root slices could be detected after one hr using the 51Cr assay. However, with the second assay, cell attachment and orientation at three, seven, 10, and 14 days were significantly higher in relation to surface-demineralized root slices than to all of the metal discs and the non-demineralized root slices. While cell attachment to the surface-ground Ti alloy discs appeared to be higher than that to the porous-surfaced Ti alloy discs at three days and seven days, cell orientation to the porous-surfaced Ti alloy discs and the non-demineralized root slices at days 7, 10, and 14 was greater than that to all of the other metal discs. These data suggest that surface geometry could affect attachment and orientation of cells in vitro.     

Oxidative nanopatterning of titanium surfaces promotes production and extracellular accumulation of osteopontin

The bone-biomaterial interface has been characterized by layers of afibrillar extracellular matrix (ECM) enriched in non collagenous proteins, including osteopontin (OPN), a multifunctional protein that in bone controls cell adhesion and ECM mineralization. Physical and chemical aspects of biomaterial surfaces have been demonstrated to affect cell-ECM-substrate interactions. The present paper described the ability of oxidative nanopatterning of titanium (Ti) surfaces to control extracellular OPN deposition in vitro. Ti discs were chemically treated by a mixture of H2SO4/H2O2 for either 30 min [Nano(30') Ti] or 4 h [Nano(4h) Ti]. Non-etched Ti discs were used as control. Primary osteogenic cells derived from newborn rat calvarial bone were plated on control and etched Ti and grown under osteogenic conditions up to 7 days. High resolution scanning electron microscopy revealed that treated Ti discs exhibited a nanoporous surface and that areas of larger nanopits were noticed only for Nano(4h) Ti. Large extracellular OPN accumulation were detectable only for Nano(4h) Ti, which was associated with OPN-positive cells with typical aspects of migrating cells. At day 3, quantitative results in terms of areas of OPN labeling were as follows: Nano(4h) Ti > Nano(30') Ti > Control Ti. In conclusion, chemically nanostructured Ti surfaces may support the enhancement of endogenous extracellular OPN deposition by osteogenic cells in vitro depending on the etching time, a finding that should be taken into consideration in strategies to biofunctionalize implant surfaces with molecules with cell adhesion capacity.     

Altered cell motility and attachment with titanium surface modifications

Background: Titanium implants are widely used in dentistry to replace lost teeth. Various surface modifications have been used to improve implant retention and osseointegration. This study is designed to compare the ability of three titanium surfaces to promote cell attachment and cell motility of cells relevant to periodontal tissues. Methods: Three clinically relevant surfaces were tested: 1) machined titanium; 2) a titanium surface roughened through acid etching (dual thermal‐etched titanium [DTET]); and 3) a titanium surface roughened with nanometer‐scale calcium phosphate deposition (nanoscale calcium phosphate–impregnated titanium [NCPIT]). Cell attachment and migration were examined for four cell types: rat osteosarcoma cells, human osteoblasts, and gingival and periodontal ligament (PDL) fibroblasts. Results: All four cell types attached to each of the three titanium surfaces equally by 2 hours, and the PDL and gingival fibroblasts generally displayed less attachment than the osteosarcoma cells and osteoblasts. The cells displayed differential motility and long‐term attachment to each of the titanium surfaces. Osteosarcoma cells displayed preferential motility on NCPIT, whereas PDL fibroblasts were more motile on machined titanium, and gingival fibroblasts moved more rapidly on both DTET and NCPIT. Osteoblasts displayed little motility on any of the titanium surfaces and lost viability on NCPIT after 24 hours. Gingival fibroblasts lost attachment to machined titanium. Conclusions: Periodontal cells displayed differential motility and long‐term attachment to titanium surfaces. Selective modification of titanium surface properties in various regions of an implant may be useful in guiding specific cell populations to specific locations where they might best aid in osseointegration and soft tissue remodeling.     

Immunolocalization of fibronectin and vitronectin receptors in human gingival fibroblasts spreading on titanium surfaces

The adhesion and spreading of human gingival fibroblasls on glass and differently processed titanium surfaces was studied by immunolocalization of vinculin and the alpha and beta subunits of the fibronectin (α₅β₁) and vitronectin (α_vβ3) receptors. Vinculin-containing focal contacts were present both at 4 and 24 h of spreading in cells grown on glass or electropolished or etched titanium surfaces but not in cells spreading on sandblasted titanium surfaces. Immunostaining for the α5 and β1 subunits of the fibronectin receptor showed only a diffuse membrane fluorescence after 4 h of cell spreading irrespective of the growth surface. The α_v and β₃ subunits of the vitronectin receptor were at this stage detected in focal contacts in cells spreading on glass or electropolished or etched titanium surfaces. In cells spreading on sandblasted titanium surfaces, however, the vitronectin receptor had only a diffuse distribution. In cells that had been allowed to spread for 24 h on glass or electropolished or etched titanium surfaces the α₅ and β₁ integrin subunits were either diffusely distributed or showed a localization typical of extracellular matrix contacts. The α_v and β₃ integrin subunits were, as earlier, localized to typical focal contacts in cells grown on glass or electropolished or etched titanium surfaces. Cells attached to sandblasted titanium surfaces still expressed all the integrin subunits only diffusely. The results show that the surface texture of the substratum can affect the expression of integrin subunits in human gingival fibroblasts. As evidenced by the recruitment of integrin subunits to focal and extracellular matrix contacts, smooth or finely grooved titanium surfaces appear to be optimal in supporting the attachment of human gingival fibroblasts.     

Response of rat bone marrow cells to differently roughened titanium discs

The purpose of the present in vitro study was to examine the effect of surface roughness on the behaviour of osteoblast-like cells. Rat bone marrow (RBM) cells were cultured on commercially pure titanium discs. The discs were used as machined (Ti M) or ground with 4000 (Ti 4000) or 320 (Ti 320) grit paper. Proliferation rate and alkaline phosphatase activity were determined, and morphology of the cells was studied with scanning electron microscopy (SEM). Besides, fluorescent markers, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to obtain quantitative and compositional information about the produced calcified extracellular matrix (ECM). Results demonstrated after 2 days of incubation no significant difference in the percentage of attached cells to all substrates. At 5 days, Ti 320 surfaces showed significantly lower (P < 0.05) cell attachment percentages compared with Ti M and Ti 4000 surfaces. At 8 days, Ti 320 surfaces showed significantly more (P < 0.05) cell attachment than the other surfaces. The Ti 4000 surfaces showed after 8 days significantly (P < 0.05) higher alkaline phosphatase activity compared to both other surfaces. At 15 days of incubation, the alkaline phosphatase activity on Ti 4000 substrates was significantly lower (P < 0.05) than on the other substrates. No significant difference in mineralized ECM formation was observed on the ground substrate compared to the machined substrates. Physicochemical analysis confirmed the apatite-like nature of the deposited ECM on all substrates. On the basis of these findings, we concluded that our in vitro study could not clearly confirm the effect of surface roughness on the proliferation, differentiation and calcification of rat bone marrow cells.     

Effect of nitride film coatings on cell compatibility

OBJECTIVE: To evaluate the cytotoxicity of nickel-based alloy surfaces after nitride film coatings. METHODS: A total of 120 disc-shaped specimens (1.5 x 12.0mm) were prepared from nickel (Ni) alloy ingots and metallurgically ground with silicon carbide (SiC) sandpaper to 1200 grit and used as the ground group. Ninety specimens from the ground group were selected and further polished with 1.0 microm aluminum powder slurry and assigned as the polished group. Titanium nitride (TiN) and titanium-aluminum nitride (TiAlN) film coatings were deposited onto 30 polished specimens each by a reactive radio frequency magnetron sputter deposition system and used as coated groups, respectively. The morphological changes and cytoskeleton of tested human gingival fibroblasts were observed using fluorescence microscopy at 3h and 24h time periods, respectively. An MTT assay was used to assess cell viability at 24h. The results were statistically analyzed (n=5, ANOVA, Scheffe', p<0.05). RESULTS: After 3h of incubation, cells began to spread on the test surfaces. Spindle-shaped fibroblasts with well-developed cytoskeleton and distinct actin fibers were observed at the 24h incubation point on the polished and coated specimens. Results of the MTT assay revealed that the TiN and TiAlN film coated groups were significantly higher in cell proliferation and viability than the polished and control groups (p<0.05). SIGNIFICANCE: The biocompatibility of Ni-based alloy was increased significantly after nitride film coating.     

The effect of titanium surface roughness on the adhesion of monocytes and their secretion of TNF-alpha and PGE2

Dental implant surfaces are important in determining the tissue/surface interaction. One of the first cells to adhere to the implant surface is the monocyte. This study examines the effect of surface roughness on monocyte adhesion and cytokine secretion. Monocyte adherence to titanium discs of 4 different degrees of surface roughness and plastic surfaces was assayed. Blood mononuclear cells were incubated for 1.5 h in 16 mm culture wells into which titanium discs had been placed. Non-adherent cells were washed off and the numbers of remaining adherent monocyte determined by DNA quantification. TNF-alpha and PGE2 secretion in media from overnight cultures of attached monocytes stimulated with lipopolysaccharide (LPS) was quantified using ELISA and RIA, respectively. Monocyte adherence to rough titanium surfaces was greater than to turned titanium surfaces, while the lowest adherence was to the plastic surface. No significant differences in adherence to 250, 75 or 25 microm blasted surfaces could be detected. The number of adherent monocytes increased with time, with maximum adhesion after 2 h of incubation. Incubation of monocytes adherent to titanium surfaces resulted in a decrease of less than 30% in their numbers over 7 days, whereas cells attached to plastic surfaces decreased to non-detectable numbers after 48 h. Porphyromonas gingivalis LPS stimulation upregulated TNF-alpha and PGE2 secretion into the media. The LPS-induced TNF-alpha and PGE2 secretion was independent of the titanium surface roughness, however the lowest amounts of TNF-alpha and PGE2 were secreted from cells attached to plastic surfaces. The results of this study indicate that the number of monocytes attached to blasted titanium surfaces is significantly greater than to machined titanium surfaces. PGE2 and TNF-alpha secretion is less influenced by titanium surface roughness.     

多孔磷酸三钙-羟基磷灰石对人牙龈成纤维细胞黏附行为的影响

目的　研究多孔磷酸三钙 羟基磷灰石 (tricalcium phosphate hydroxyapatite ,TCP HA)复合材料对人牙龈成纤维细胞黏附行为的影响。方法　应用离子束辅助沉积法在纯钛试件表面制备多孔TCP HA复合涂层材料和羟基磷灰石 (hydroxyapatite,HA)涂层材料 ,定量对比人牙龈成纤维细胞在涂层和未涂层材料表面初期黏附、增殖、细胞铺展面积、细胞外基质和黏着斑形成的情况。结果　TCP HA和HA涂层材料表面黏附的细胞数、细胞铺展面积高于纯钛未涂层组 ,差异有显著性(P <0 0 5 ) ,黏着斑的形成早于未涂层组 ;TCP HA表面黏附的细胞数和Ⅰ型胶原的形成都高于纯钛未涂层组和HA涂层组。在培养 2 4h后TCP HA组表面黏附细胞数为 198 1± 2 7 7,Ⅰ型胶原形成的荧光强度为 15 4 10± 31 5 6 ,同纯钛组表面的细胞数 ( 12 5 1± 2 9 9)和Ⅰ型胶原荧光强度( 132 6 3± 35 2 6 )相比 ,差异有显著性 (P <0 0 5 )。结论　与纯钛未涂层和HA涂层材料相比 ,多孔TCP HA复合涂层材料更有利于人牙龈成纤维细胞的初期黏附 ,具有更良好的生物相容性     

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.