The effects of titanium nitride-coating on the topographic and biological features of TPS implant surfaces

Objectives

Titanium nitride (TiN) coating has been proposed as an adjunctive surface treatment aimed to increase the physico-mechanical and aesthetic properties of dental implants. In this study we investigated the surface characteristics of TiN-coated titanium plasma sprayed (TiN-TPS) and uncoated titanium plasma sprayed (TPS) surfaces and their biological features towards both primary human bone marrow mesenchymal stem cells (BM-MSC) and bacterial cultures.

Methods

15 mm × 1 mm TPS and TiN-TPS disks (P.H.I. s.r.l., San Vittore Olona, Milano, Italy) were topographically analysed by confocal optical profilometry. Primary human BM-MSC were obtained from healthy donors, isolated and expanded. Cells were seeded on the titanium disks and cell adhesion, proliferation, protein synthesis and osteoblastic differentiation in terms of alkaline phosphatase activity, osteocalcin synthesis and extracellular mineralization, were evaluated. Furthermore, adhesion and proliferation of Streptococcus pyogenes and Streptococcus sanguinis on both surfaces were also analysed.

Results

TiN-TPS disks showed a decreased roughness (about 50%, p < 0.05) and a decreased bacterial adhesion and proliferation compared to TPS ones. No difference (p > 0.05) in terms of BM-MSC adhesion, proliferation and osteoblastic differentiation between TPS and TiN-TPS surfaces was found.

Conclusions

TiN coating showed to modify the topographical characteristics of TPS titanium surfaces and to significantly reduce bacterial adhesion and proliferation, although maintaining their biological affinity towards bone cell precursors.     

The effects of scaling titanium implant surfaces with metal and plastic instruments on cell attachment

This study examined the ability of tissue culture fibroblasts to attach and colonize on the surface of pure titanium dental implants following instrumentation of the implant surface with curettes of dissimilar composition. Pure titanium dental implants were scaled with a plastic, titanium-alloy, or stainless steel curette and then immersed in a cell suspension of 3T3 fibroblasts. Counts of attached cells were made at 24 and 72 hours; the implants were then processed for scanning electron microscopy (SEM). At 24 hours, only surfaces scaled with a stainless steel curette showed a significant reduction in number of attached cells relative to untreated control surfaces. At 72 hours, both stainless steel and titanium-alloy curette instrumented surfaces showed significantly fewer attached cells than untreated control surfaces, with the greatest reduction in cell attachment observed on the stainless steel curette instrumented surfaces. SEM observations showed that fibroblasts on stainless steel instrumented surfaces tended to show a somewhat rounded morphology and a relatively reduced degree of spreading: while fibroblasts on untreated control, plastic, or titanium-alloy instrumented surfaces showed a well-spread, polygonal morphology, more typical of fibroblasts in favorable culture conditions. To the extent that such observations of cell attachment and morphology are indicative of in vivo biocompatibility, these findings could have clinical implications for the proper maintenance of titanium dental implants.     

Characterization of sterilized CP titanium implant surfaces

Surface analysis techniques and in vitro biologic assays were used to characterize sterilized commercially pure titanium surfaces. Significant surface alterations were observed following sterilization treatments. These alterations led to decreased fibroblast cell attachment and altered cellular spreading phenomena compared to nonsterilized control surfaces.     

Effect of plastic-covered ultrasonic scalers on titanium implant surfaces

Objectives: Maintaining oral health around titanium implants is essential. The formation of a biofilm on the titanium surface will influence the continuing success of the implant. These concerns have led to modified ultrasonic scaler instruments that look to reduce implant damage while maximising the cleaning effect. This study aimed to assess the effect of instrumentation, with traditional and modified ultrasonic scalers, on titanium implant surfaces and to correlate this with the oscillations of the instruments. Materials and methods: Two ultrasonic insert designs (metallic TFI‐10 and a plastic‐tipped implant insert) were selected. Each scaler probe was scanned using a scanning laser vibrometer, under loaded and unloaded conditions, to determine their oscillation characteristics. Loads were applied against a titanium implant (100g and 200 g) for 10 s. The resulting implant surfaces were then scanned using laser profilometry and scanning electron microscopy (SEM). Results: Insert probes oscillated with an elliptical motion with the maximum amplitude at the probe tip. Laser profilometry detected defects in the titanium surface only for the metallic scaler insert. Defect widths at 200 g high power were significantly larger than all other load/power conditions (P<0.02). Using SEM, it was observed that modifications to the implant surface had occurred following instrumentation with the plastic‐tipped insert. Debris was also visible around the defects. Conclusions: Metal scalers produce defects in titanium implant surfaces and load and power are important factors in the damage caused. Plastic‐coated scaler probes cause minimal damage to implant surfaces and have a polishing action but can leave plastic deposits behind on the implant surface. To cite this article:
Mann M, Parmar D, Walmsley AD and Lea SC. Effect of plastic covered ultrasonic scalers on titanium implant surfaces.
Clin. Oral Impl. Res. 23 , 2012; 76–82
doi: 10.1111/j.1600‐0501.2011.02186.x     

Bone tissue response to plasma-nitrided titanium implant surfaces

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration.

Objective

The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments.

Material and Methods

Surface treatments consisted of 20% N₂ and 80% H₂, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses.

Results

Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area.

Conclusion

Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces.     

Red blood cell and platelet interactions with titanium implant surfaces

The influence of the micro-roughened surface, produced by dual acid-etching (DAE) of machined commercially pure titanium, on initial blood cell/implant interactions was investigated by observing the blood components remaining at the implant surface following freeze-fracture of clotted, and fixed, human blood. Glass surfaces were also used for immunolabelling studies to identify fibrin and platelets. The interface comprised predominantly fibrin and red blood cells (RBCs). The difference in distribution of RBCs was statistically significant (P < 0.05) at 10 min of blood/implant contact, but diminished thereafter. Micro-roughened DAE implant surfaces showed, qualitative, more platelets than machined surfaces, while the textured glass surfaces demonstrated increased platelet aggregation. We believe that these early blood cell/implant interactions may play a key role in the osteoconduction stage of peri-implant bone healing response to micro-roughened implants.     

In vivo and in vitro biofilm formation on two different titanium implant surfaces

Objectives: The aim of the present in vitro and human in vivo study was twofold: first, to evaluate the initial biofilm formation on different titanium implant surfaces by means of two highly sensitive fluorescent techniques and, second, to correlate these findings to different surface properties. Materials and methods: In vivo biofilm formation was induced on purely machined (Pt) and on sand‐blasted and acid‐etched titanium (Prom) specimens, which were mounted buccally on individual splints and worn by six study participants for 12 h. In vitro bacterial adhesion was also investigated after incubation with Streptococcus sanguinis suspension (37°C, 2 h). Adherent bacteria were quantified by the following fluorescence techniques: Resazurin staining in combination with an automated fluorescence reader or live/dead cell labeling and fluorescence microscopy. Surface roughness (R_a) was determined with a perthometer, and surface free energy (SFE) was measured with a goniometer. Results: Prom showed a significantly higher median R_a (0.95 μm) and a significantly lower median SFE (18.3 mJ/m²) than Pt (R_a=0.15 μm; SFE=39.6 mJ/m²). The in vitro and in vivo tests showed a significantly higher bacterial adhesion to Prom than to Pt, and the initial biofilm formation on Pt corresponded to the circular surface modifications on the machined substratum. Both observations may be attributed to the predominant influence of surface roughness on bacterial adhesion. No significant differences in the percentage of dead cells among all adhering bacteria were found between Prom (23.7%) and Pt (29.1%). Ectopic solitary epithelial cells from the oral mucosa – strongly adhering to the substratum – were found on each Prom specimen, but not on any of the Pt surfaces. Conclusions: Initial bacterial adhesion to differently textured titanium surfaces is primarily influenced by R_a, whereas the influence of SFE seems to be of only minor importance. Therefore, the micro‐structured parts of an implant that are exposed to the oral cavity should be highly polished to prevent plaque accumulation. Both tested fluorometric techniques proved to be highly sensitive and reproducible in the quantification of biofilm formation on titanium implant surfaces. To cite this article:
Bürgers R, Gerlach T, Hahnel S, Schwarz F, Handel G, Gosau M. In vivo and in vitro biofilm formation on two different titanium implant surfaces.
Clin. Oral Impl. Res. 21 , 2010; 156–164
doi: 10.1111/j.1600‐0501.2009.01815.x     

钛种植体表面纳米改性及其与机体免疫应答

采用纳米颗粒紧压法、离子束辅助沉积技术、表面化学处理和阳极氧化法等辅助方式将种植体表面结构进行改性。种植体植入后可能引起机体免疫反应。研究显示,多形核白细胞、巨噬细胞、单核细胞和树突细胞在机体天然免疫反应中起重要作用。这些细胞针对种植体表面分别介导不同的免疫反应。一些细胞因子参与免疫反应的调节,对于消除该区域的炎症,提高骨整合,促进伤口愈合提供帮助。本文就钛种植体表面的纳米改性方法、钛种植体表面纳米改性与机体免疫应答之间的联系等研究进展作一综述。     

Surface chemistry effects of topographic modification of titanium dental implant surfaces: 1. Surface analysis

PURPOSE: To analyze the surface composition of 34 different commercially available titanium dental implants. MATERIALS AND METHODS: Surface composition was evaluated by x-ray photoelectron spectroscopy (XPS). Samples were divided into 4 groups, depending on their surface topography (machined, sandblasted, acid etched, or plasma sprayed). RESULTS: Statistical analysis of the data showed a clear relationship between surface composition and topography, which can be easily accounted for by the chemical effects of the surface treatment performed. On average, acid-etched and plasma-sprayed surfaces had higher titanium and lower carbon concentration than machined surfaces. DISCUSSION AND CONCLUSION: Current studies aimed at the evaluation of implants with different topography should not implicitly assume that topography is the only variable controlling the biologic response. Rather, when comparing different topographies, it should be taken into account that surface chemistry may be a variable as well.     

钛种植体表面磷酸化与仿生矿化的实验研究

目的 探讨钛表面磷酸化处理的方法,并观察磷酸化钛表面在模拟体液内进行仿生矿化的实验效果,以期为钛种植体表面改性提供新的研究思路.方法 用磷酸对钛表面进行酸蚀处理,再以此为仿生模板进行体外仿生矿化研究.结果 钛磷酸化处理后形成粗糙、多孔的表面,再经高温高压处理,生成与钛表面化学键合的Ti( H2PO4)3晶体层,此层富含- OH及- PO43-离子,具备生物矿化诱导功能,从而活化钛种植体表面.结论 磷酸酸蚀可以实现对钛种植体表面的磷酸化改性.     

Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces

Objectives

Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces.

Materials and methods

EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction.

Results

Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces.

Conclusions

The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities.

Clinical relevance

In correlation with recent clinical studies these results underline the hypothesis that EPC could promote and increase neovascularization by secreting paracrine factors which support osseointegration of dental implants.     

Comparison of human mandibular osteoblasts grown on two commercially available titanium implant surfaces

BACKGROUND: Surface characteristics play a major role in determining tissue response to implants and therefore their clinical outcome. The aim of the present study was to compare two commercially available titanium surfaces: plasma sprayed (TPS) and sand-blasted, acid-etched surface (SLA). METHODS: The surfaces were characterized by roughness testing, scanning electronic microscopy (SEM), Raman spectroscopy, and protein adsorption to determine their microtopographic and chemical properties. The effect of the surfaces on human mandibular osteoblasts was then studied in terms of cell morphology, adhesion, proliferation, and differentiation. Human osteoblasts from the mandible were cultured on these two surfaces and evaluated at 3, 6, 24, and 48 hours to determine cell attachment and morphology. Growth and differentiation kinetics were subsequently investigated by evaluating cell growth, alkaline phosphatase activity, osteocalcin and osteoprotegerin production at 7, 14, and 21 days. RESULTS: Although roughness was quite similar, the two surfaces presented strong differences in their topography, and cell morphology varied as a consequence. Osteoblasts on SLA appeared more elongated and spindle shaped than those on TPS, and their adhesion at 3 and 6 hours was weaker, but reached that of cells on TPS at hour 24. Cell proliferation was greater on SLA surfaces but differentiation parameters; i.e., alkaline phosphatase and osteocalcin, provided better results on TPS surfaces. Osteoprotegerin production was enhanced on TPS surfaces at days 14 and 21. CONCLUSION: Although cells grown on both surfaces exhibited good adhesion capabilities, a well-differentiated osteoblastic phenotype, and maintained a clear proliferation potential, our study suggests that plasma-sprayed treatment offers a better performance than SLA by creating, at least in the early phases, better conditions for tissue healing.     

Biological and physicochemical implications of the aging process on titanium and zirconia implant material surfaces

Statement of problemChanges in physicochemical properties because of implant material aging and natural deterioration in the oral environment can facilitate microbial colonization and disturb the soft-tissue seal between the implant surfaces.PurposeThe purpose of this in vitro study was to investigate the effect of aging time on the physicochemical profile of titanium (Ti) and zirconia (ZrO₂) implant materials. Further microbiology and cell analyses were used to provide insights into the physicochemical implications of biological behavior.Material and methodsDisk-shaped specimens of Ti and ZrO₂ were submitted to roughness, morphology, and surface free energy (SFE) analyses before nonaging (NA) and after the aging process (A). To simulate natural aging, disks were subjected to low-temperature degradation (LTD) by using an autoclave at 134 ºC and 0.2 MPa pressure for 20 hours. The biological activities of the Ti and ZrO₂ surfaces were determined by analyzing Candida albicans (C. albicans) biofilms and human gingival fibroblast (HGF) cell proliferation. For the microbiology assays, a variance analysis method (ANOVA) was used with the Tukey post hoc test. For the evaluation of cellular proliferation, the Kruskal-Wallis test followed by Dunn multiple comparisons were used.ResultsTi nonaging (TNA) and ZrO₂ nonaging (ZNA) disks displayed hydrophilic and lipophilic properties, and this effect was sustained after the aging process. Low-temperature degradation resulted in a modest change in intermolecular interaction, with 1.06-fold for TA and 1.10-fold for ZA. No difference in biofilm formation was observed between NA and A disks of the same material. After 48 hours, the viability of the attached HGF cells was very similar to that in the NA and A groups, regardless of the tested material.ConclusionThe changes in the physicochemical properties of Ti and ZrO₂ induced by the aging process do not interfere with C. albicans biofilm formation and HGF cell attachment, even after long-term exposure.