Surface properties of titanium and zirconia dental implant materials and their effect on bacterial adhesion

Objectives

Zirconia ceramic material has been widely used in implant dentistry. In this in vitro study the physiochemical properties of titanium and zirconia materials were investigated and the affinity of different bacteria to different materials was compared.

Methods

Disc samples with different surface states were used: polished partially stabilized zirconia (PZ), titanium blasted with zirconia (TBZ), titanium blasted with zirconia then acid etched (TBZA), and polished titanium (PT) as a control. Surface topography was examined using scanning electron microscopy and profilometry. Contact angle, surface free energy (SFE), surface microhardness and chemical composition were determined.Disc samples were separately incubated with Streptococcus mitis and Prevotella nigrescens, either with or without pre-coating with human saliva, for 6 h and the surface area covered by bacteria was calculated from fluorescence microscope images.

Results

PZ and TBZ exhibited lower surface free energy and lesser surface wettability than PT. Also, PZ and TBZ surfaces showed lower percentage of bacterial adhesion compared with control PT surface.

Conclusions

The zirconia material and titanium blasted with zirconia surface (TBZ surface) showed superior effect to titanium material in reducing the adhesion of the experimented bacteria especially after coating with saliva pellicle. Modifying titanium with zirconia lead to have the same surface properties of pure zirconia material in reducing bacterial adhesion.SFE appears to be the most important factors that determine initial bacterial adhesion to smooth surface.     

Influence of a Nanoporous Zirconia Implant Surface of on Cell Viability of Human Osteoblasts

Purpose : The dense nonretentive surface of zirconia implants was modified into a nanoporous surface using selective infiltration etching surface treatment. The aim of this study was to investigate the influence of such a nanoporous modified zirconia surface on the attachment of human osteoblasts. Materials and Methods : Human osteoblasts were cultured for 21 days on (i) selective infiltration etched zirconia (nanoporous surface), (ii) polished zirconia, (iii) polished titanium, or (iv) airborne particle abraded acid etched (SLA) titanium disks. After the culture period the following parameters were assessed: number of cells, the morphology of the cells, the attachment of the cells, alkaline phosphatase activity, and the level of total protein (α= 0.05). Results : Statistical analysis revealed a significantly higher cell count on the third (F = 17.4, p < 0.001) and eighth day (F = 163, p < 0.001) for nanoporous zirconia and SLA titanium surfaces compared to polished specimens. The number of cells (nanoporous zirconia 160 ± 20/mm², SLA titanium 133 ± 15/mm²) and cell size (nanoporous zirconia 50.7 ± 3 μm, SLA titanium 42.5 ± 4 μm) were significantly higher than polished specimens. Nanoporous zirconia specimens demonstrated comparable alkaline phosphatase activity (0.0036 ± 0.0035 ng/μl) and intracellular protein content (72.7 ± 0.9 ng/μl) compared to other tested groups. Scanning electron microscopy revealed that cells attached on the polished surface using finger‐like processes, whereas on the nanoporous surface, finger‐like processes were not observed, as the cell membrane appeared to be in close proximity to the underlying surface. Conclusion : The findings of this study suggest that a nanoporous zirconia surface favors cell growth and attachment compared to a polished surface. It was proposed that a nanoporous zirconia surface may improve clinical performance of zirconia implants.     

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.     

In Vitro Biofilm Formation on Titanium and Zirconia Implant Surfaces

Background: It has been hypothesized that zirconia might have a reduced bacterial adhesion compared with titanium; however, results from experimental studies are rather controversial. The aim of the present study is to compare biofilm formation on zirconia and titanium implant surfaces using an in vitro three‐species biofilm and human plaque samples. Methods: Experimental disks made of titanium (Ti) or zirconia (ZrO₂) with a machined (M) or a sandblasted (SLA) and acid‐etched (ZLA) surface topography were produced. An in vitro three‐species biofilm or human plaque samples were applied for bacterial adhesion to each type of disk, which after 72 hours of incubation was assessed using an anaerobic flow chamber model. Results: Zirconia showed a statistically significant reduction in three‐species biofilm thickness compared with titanium (ZrO₂‐M: 8.41 μm; ZrO₂‐ZLA: 17.47 μm; Ti‐M: 13.12 μm; Ti‐SLA: 21.97 μm); however, no differences were found regarding three‐species‐biofilm mass and metabolism. Human plaque analysis showed optical density values of 0.06 and 0.08 for ZrO₂‐M and ZrO₂‐ZLA, and values of 0.1 and 0.13 for Ti‐M and Ti‐SLA, respectively; indicating a statistically significant reduction in human biofilm mass on zirconia compared with titanium. Additionally, zirconia revealed a statistically significant reduction in human plaque thickness (ZrO₂‐M: 9.04 μm; ZrO₂‐ZLA: 13.83 μm; Ti‐M: 13.42 μm; Ti‐SLA: 21.3 μm) but a similar human plaque metabolism compared with titanium. Conclusion: Zirconia implant surfaces showed a statistically significant reduction in human plaque biofilm formation after 72 hours of incubation in an experimental anaerobic flow chamber model compared with titanium implant surfaces.     

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.     

Initial bacterial adhesion on resin, titanium and zirconia in vitro

PURPOSE

The aim of this in vitro study was to investigate the adhesion of initial colonizer, Streptococcus sanguis, on resin, titanium and zirconia under the same surface polishing condition.

MATERIALS AND METHODS

Specimens were prepared from Z-250, cp-Ti and 3Y-TZP and polished with 1 µm diamond paste. After coating with saliva, each specimen was incubated with Streptococcus sanguis. Scanning electron microscope, crystal violet staining and measurement of fluorescence intensity resulting from resazurin reduction were performed for quantifying the bacterial adhesion.

RESULTS

Surface of resin composite was significantly rougher than that of titanium and zirconia, although all tested specimens are classified as smooth. The resin specimens showed lower value of contact angle compared with titanium and zirconia specimens, and had hydrophilic surfaces. The result of scanning electron microscopy demonstrated that bound bacteria were more abundant on resin in comparison with titanium and zirconia. When total biofilm mass determined by crystal violet, absorbance value of resin was significantly higher than that of titanium or zirconia. The result of relative fluorescence intensities also demonstrated that the highest fluorescence intensity was found on the surface of resin. Absorbance value and fluorescence intensity on titanium was not significantly different from those on zirconia.

CONCLUSION

Resin specimens showed the roughest surface and have a significantly higher susceptibility to adhere Streptococcus sanguis than titanium and zirconia when surfaces of each specimen were polished under same condition. There was no significant difference in bacteria adhesion between titanium and zirconia in vitro.     

Behavior of CAL72 osteoblast-like cells cultured on zirconia ceramics with different surface topographies

OBJECTIVES: Because of its inherent strength, biocompatibility, and tooth-like color, zirconia ceramics have the potential to become an alternative to titanium as dental implant material. This study aimed at investigating the osteoblastic response to yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with different surface topographies. METHODS: CAL72 osteoblast-like cells were cultured on machined (TZP-m), airborne particle abraded (TZP-s), and airborne particle abraded and acid-etched Y-TZP (TZP-sa) surfaces. Polystyrene and airborne particle abraded with large grit and acid-etched (SLA) titanium served as a reference control. The surface topography was examined by scanning electron microscopy (SEM) and profilometry. At culture days 3, 6, and 12, cell proliferation, at day 12 cell morphology, and cell-covered surface area were determined. RESULTS: The surface roughness of Y-TZP was increased by airborne particle abrasion and additionally by acid etching. No statistically significant differences were found between average roughness (R(a)) and maximum peak-to-valley height (R(p-v)) values of airborne particle abraded and acid-etched Y-TZP and SLA titanium. Whereas the cell proliferation assay revealed statistically significant greater values at day 3 for surface-treated Y-TZP and polystyrene cultures as compared with machined Y-TZP, no differences between the Y-TZP groups, SLA titanium, and polystyrene were observed at culture days 6 and 12. CONCLUSIONS: Cell morphology and cell-covered surface area were not affected by the type of substrate. The results suggest that roughened Y-TZP is an appropriate substrate for the proliferation and spreading of osteoblastic cells.     

Adhesion pattern and growth of primary human osteoblastic cells on five commercially available titanium surfaces

Objective: The aim of this study is to analyze the morphology and proliferation of human osteoblastic cells in vitro on five commercially available titanium surfaces. Materials and methods: Human primary cells of the osteoblastic lineage were obtained from bone explants. The cells were plated on polished (T1), machined (T2), sand‐blasted/acid‐etched (T3), sand‐blasted/acid‐etched, modified with hydrogen peroxide rinse (T4), and plasma‐sprayed titanium (T5) disks. Cell morphology was studied after 6, 24, 72 h, 7 and 14 days of culture by scanning electron microscopy. The formation and distribution of focal adhesions was investigated by immunocytochemical staining at 3, 6 and 24 h. Cell growth was measured by an MTT assay after 3, 7 and 9 days of culture. Moreover, the production of osteocalcin and osteoprotegerin (OPG) was evaluated in the supernatants by ELISA. Results: Morphological analysis revealed that substrate topography profoundly affected cells' shape and their anchoring structures. Large lamellipodia were formed on polished and machined surfaces, while thin filopodia were more frequently observed on T3 and T4 samples. Moreover, cells formed stronger focal adhesions on T3 and T4 surfaces, and cell proliferation was higher on rough surfaces. Osteocalcin production was higher on the T4 surface, whereas OPG steadily increased on every surface. Conclusions: Taken together, these data show that all the surfaces allowed cell attachment, adhesion and proliferation, but T4 and T5 surfaces appeared to be a better substrate for the adhesion, proliferation and differentiation of cells of the osteoblastic lineage. To cite this article:
Passeri G, Cacchioli A, Ravanetti F, Galli C, Elezi E, Macaluso GM. Adhesion pattern and growth of primary human osteoblastic cells on five commercially available titanium surfaces.
Clin. Oral Impl. Res. 21 , 2010; 756–765.
doi: 10.1111/j.1600‐0501.2009.01906.x     

Titanium surface modification and its effect on the adherence of Porphyromonas gingivalis: an in vitro study

AIM: Titanium dental implants are an important treatment option in the replacement of missing teeth. Implant failures can, however, occur and may be promoted by the loss of tissue as a result of local bacterial infection (peri-implantitis). OBJECTIVES: Bacterial adherence to implant surfaces is believed to be influenced by material surface roughness and surface-free energy parameters. Consequently, the aim of this study was to modify these properties of titanium and identify what effect these modifications had on subsequent bacterial adherence. Materials and methods: In this study, 16 titanium samples of different roughness (R(a) 34.57-449.42 nm) were prepared using specific polishing procedures. A further six samples were chemically altered by argon plasma discharge treatment and immersion in silane solutions to produce different surface hydrophobicities. An in vitro adhesion assay using Porphyromonas gingivalis was used to assess the effect of modification on bacterial adherence. RESULTS: A significant reduction in adhesion to materials categorised as being 'very smooth' (R(a) 34.57+/-5.79 nm) was evident. This reduction did not occur with 'smooth' (R(a) 155.00+/-33.36 nm), 'rough' (R(a) 223.24+/-9.86 nm) or 'very rough' (R(a) 449.42+/-32.97 nm) surfaces. Changing material surface hydrophobicity was also not found to effect bacterial adhesion. CONCLUSIONS: Adhesion of P. gingivalis to titanium was inhibited at surface roughness levels below those generally encountered for implant collars/abutments (R(a) 350 nm). Considerations of these findings may be beneficial in the production of titanium implants in order to reduce bacterial colonisation.     

振荡培养条件下氧化锆陶瓷和钛合金表面粗糙度与细菌黏附的比较

目的：振荡培养条件下比较氧化锆陶瓷和钛合金抛光后表面粗糙度的差异及变形链球菌在其表面的黏附能力。方法：制作氧化锆陶瓷和钛合金样本各6个。A组氧化锆陶瓷用EVE专用抛光轮高度抛光,B组钛合金原始铸件依次用粗砂纸、水砂纸（依次为200目、600目、800目、1000目、1200目、1500目、2000目）逐级磨光,再用抛光轮抛光。用表面粗糙度检测仪测量各组样本的表面粗糙度。将两组样本置于变形链球菌悬浮液中,37℃振荡培养条件下培养1h。荧光显微镜下计数黏附变形链球茵的数量,并通过扫描电子显微镜观察各样本的表面形貌。结果：A、B两组的表面粗糙度分别为（0．0548±0．027）μm、（0．0483±0．006）μm。变形链球菌在A、B两组样本表面的黏附数分别为4．2222±1．019、8．5417±2．208。经统计学分析,A、B两组表面粗糙度差异无显著性（P〉0．05）,A组与B组样本变形链球菌黏附数差异有显著性（P〈0．05）。扫描电镜显示,氧化锆陶瓷抛光组试件表面散在少量细小孔隙,而钛合金抛光组试件表面未见少量细小空隙,但有较多裂隙和凹陷。结论：氧化锆陶瓷和钛合金抛光后表面能达到同样光滑,但钛合金表面比氧化锆陶瓷表面更容易黏附变形链球茵。     

Neural response to sandblasted/acid-etched, TiO-blasted, polished, and mechanochemically polished/nanostructured titanium implant surfaces

The purpose of this study was to explore morphologic, functional, and behavioral effects of rough (sandblasted-large grid/acid-etched (SLA) and TiO2 blasted), mechanically polished, and mechanochemically polished titanium implant surfaces on nerves. The compound action potentials (cAPs) of sciatic nerves of sacrificed Wistar rats (n=10) were quantified at the in vitro level, while contacting disk-shaped test specimens. The test specimens were also implanted directly on the sciatic nerves of another group of animals (n=33), hot-plate tests were undertaken for 10 consecutive days, and then the animals were sacrificed. Quantification of signal transduction speeds and cAPs of the nerves of these animals were undertaken at the in vitro level. Finally, the nerves were processed for histologic analysis. The signal transduction speeds and duration of cAPs of all groups were similar (P>0.05), whereas the amplitudes of cAPs of nerves contacting SLA implants were higher than those of TiO2 blasted and mechanochemically polished surfaces (P<0.05). Response latencies of nerves contacting mechanically polished specimens were slightly higher than the other groups (P>0.05). Histologic evaluations did not reveal any signs of adverse tissue response adjacent to specimens tested. Rough and polished titanium implant surfaces lead to similar neural response in vivo and in vitro that fall into physiologic limits.     

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.     

不同种植体表面改性对细菌生物膜的影响

目的:研究临床常用的3种钛种植体不同表面处理对口腔内常见菌群牙龈卟啉单胞菌(Porphyromanusgingivalis,P.gingivalis)、具核梭杆菌(Fusobacterium nucleatum,F.nucleatum)及血链球菌(Streptococcus sanguis,S.sanguis)生物膜黏附的影响。方法:将钛片分成3组进行表面改性处理,分别为:电解沉积羟基磷灰石(HA)组、微弧氧化(MAO)组和大颗粒喷砂酸蚀(SLA)组,进行表面性能检测;在3组钛片上分别培养Pg、Fn及Ss 4 d,通过菌落形成单位(CFU)法、噻唑蓝(MTT)法和扫描电子显微镜(SEM)探究细菌的黏附情况。结果:(1)SEM观察表面形貌可见HA组表面大量不规则的棒状结构;MAO表面“火山口”样结构,孔径在0.1~1μm之间;SLA表面为不规则凹陷,大小不一且边缘锋利。3组表面粗糙度Ra值:SLA组0.05);Pg生物膜在MAO组钛片上活性最高,与另外2组有统计学差异(P<0.01)。(3)利用SEM观察显示,细菌活性与种植体表面形态结构有关。结论:细菌在种植体表面黏附受到表面形貌影响,与粗糙度及物理构型有关。对于Pg、Ss和Fn 3种细菌,SLA在3种表面处理中细菌粘附量最少。     

喷砂酸蚀对超细晶纯钛表面MC3T3-E1细胞粘附与增殖的影响

目的:研究喷砂酸蚀对超细晶纯钛表面MC3T3-E1细胞粘附与增殖的影响。方法:将超细晶纯钛棒和纯钛棒切割为直径6 mm,厚度3 mm钛片试件,试验组为喷砂酸蚀超细晶纯钛组,对照组分别为未处理的超细晶纯钛组和喷砂酸蚀纯钛组。在对其表面形貌特征和亲水性进行检测后,在试件表面接种MC3T3-E1细胞,观察细胞的初期粘附情况,测定细胞密度,存活和生长状态。结果:喷砂酸蚀超细晶纯钛后,其表面形成大量微小的弹坑状凹陷,且表面具有良好的亲水性。接种细胞后,喷砂酸蚀超细晶纯钛初期粘附优于对照组;细胞密度在培养中后期优于对照组;而细胞活性在培养中期优于两对照组,培养后期3组间无明显差异。结论:喷砂酸蚀超细晶纯钛的表面性能得到改善,能诱导MC3T3-E1细胞在其表面粘附和增殖,可作为纯钛种植体种植体的替代材料。     

Bacterial colonization of zirconia ceramic surfaces: an in vitro and in vivo study

PURPOSE: The microbial colonization of new ceramic materials developed for abutment manufacturing was assessed. MATERIALS AND METHODS: The materials used in these experiments were disks of 'as-fired' and 'rectified' ceramic material made of tetragonal zirconia polycrystals stabilized with yttrium (Y-TZP) and commercially pure grade 2 titanium (Ti) with corresponding eluates. They were tested in vitro with the following bacteria: Streptococcus mutans, S. sanguis, Actinomyces viscosus, A. naeslundii, and Porphyromonas gingivalis. Proliferation was evaluated on plates by inhibitory halos around pits, previously inoculated with eluates obtained from the materials. Bacterial adhesion on materials was quantified by spectrophotometric evaluation of the slime production by the same bacteria. Moreover, early bacterial adhesion was evaluated in human volunteers and observed with SEM. RESULTS: No inhibition of bacterial proliferation using eluates was observed. In vitro as-fired and rectified Y-TZP showed significantly more adherent S. mutans than did Ti disks, while S. sanguis seemed to adhere easily to Ti specimens. No differences were noted for Actinomyces spp and P. gingivalis. In vivo Y-TZP accumulated fewer bacteria than Ti in terms of the total number of bacteria and presence of potential putative pathogens such as rods. No differences were observed between rectified and as-fired Y-TZP. DISCUSSION: Overall, Y-TZP accumulates fewer bacteria than Ti. CONCLUSION: Y-TZP may be considered as a promising material for abutment manufacturing.     

The angiogenic behaviors of human umbilical vein endothelial cells (HUVEC) in co-culture with osteoblast-like cells (MG-63) on different titanium surfaces

Objectives

Interaction between osteogenesis and angiogenesis plays an important role in implant osseointegration. In the present study we investigated the influence of titanium surface properties on the angiogenic behaviors of endothelial cells grown in direct contact co-culture with osteoblasts.

Methods

Human umbilical vein endothelial cells (HUVECs) and osteoblast-like cells (MG-63 cells) were grown in direct co-culture on the following titanium surfaces: acid-etched (A), hydrophilic A (modA), coarse-gritblasted and acid-etched (SLA) and hydrophilic SLA (SLActive). Cell proliferation was evaluated by cell counting combined with flow cytometry. The expression of von Willebrand Factor (vWF), thrombomodulin (TM), endothelial cell protein C receptor (EPCR), E-Selectin, as well as vascular endothelial growth factor (VEGF) receptors Flt-1 and KDR in HUVECs and VEGF in MG-63 were measured by qPCR. The dynamic behavior of endothelial cells was recorded by time-lapse microscopy.

Results

Proliferation of HUVECs was highest on A, followed by SLA, modA and SLActive surfaces. The expression of vWF, TM, EPCR, E-Selectin and Flt-1 in HUVECs was significantly higher on A than on all other surfaces. The expression of KDR in HUVECs grown on A surface was below detection limit. VEGF expression in MG-63 cells was significantly higher on SLActive vs SLA and modA vs A surfaces. Time-lapse microscopy revealed that HUVECs moved quickest and formed cell clusters earlier on A surface, followed by SLA, modA and SLActive surface.

Conclusions

In co-culture conditions, proliferation and expression of angiogenesis associated genes in HUVECs are promoted by smooth hydrophobic Ti surface, which is in contrast to previous mono-culture studies.     

等离子渗氮表面处理对纯钛材料细菌黏附能力的影响

目的：研究等离子渗氮对钛表面的组织结构、性能及对变形链球菌黏附的影响。方法：将相同规格的钛片60片经逐级抛光后随机分成抛光组和等离子渗氮表面处理组。测量所有试件表面的粗糙度值,并采用扫描电镜、Axiovert 25CA光学图像分析仪及GDA750对钛表面渗镀层的表面形貌情况进行分析;将材料接种于变形链球菌悬液1h,在荧光显微镜下计数黏附细菌的数量。结果：等离子渗氮表面处理仅使纯钛表面粗糙度略微增加,并均在0.2μm以下;扫描电镜显示,等离子渗氮表面处理后材料表面的原始划痕消失;GDS检测分析结果表明,等离子渗氮表面处理后,表面主要由氮化钛化合物组成。经渗氮处理后,纯钛黏附细菌的量显著减少。结论：纯钛经等离子渗氮表面处理后形成了稳定的改性层,且能减少细菌的黏附。     

钛表面形貌和亲水性表面对成骨细胞增殖、分化的影响

目的:通过体外实验研究普通喷砂酸蚀纯钛表面和亲水性喷砂酸蚀纯钛表面对成骨细胞增殖、分化等生物学行为的影响。方法:纯钛片表面分别采用光滑处理(smooth pretreated Ti,PT)、大颗粒喷砂酸蚀表面处理(sand-blasted,large-grit,acid-etched,SLA)及亲水性化学活化大颗粒喷砂酸蚀表面处理(chemically-modified SLA,modSLA/SLActive),在表面接种MC3T3-E1成骨细胞,采用MTT、碱性磷酸酶半定量测试以及茜素红染色检测其对成骨细胞增殖、分化的影响,并采用实时荧光定量PCR检测成骨细胞在不同材料表面骨功能基因表达的差异。应用SAS 9.0软件包对数据进行统计学分析。结果:与光滑钛表面相比,普通喷砂酸蚀钛表面能通过促进ALP、钙基质的分泌和成骨功能基因(Runx2、OSX、OCN和OPN)的表达而显著抑制成骨细胞增殖并促进其分化。在表面粗糙度的基础上增加亲水性,可使这一效应更加明显。结论:表面粗糙度和亲水性是影响成骨细胞生物学行为的重要因素,粗糙钛表面能显著抑制成骨细胞增殖,促进其分化,亲水性的粗糙钛表面促进成骨细胞分化的作用更加显著。     

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.