Surface treatments of titanium dental implants for rapid osseointegration.

The osseointegration rate of titanium dental implants is related to their composition and surface roughness. Rough-surfaced implants favor both bone anchoring and biomechanical stability. Osteoconductive calcium phosphate coatings promote bone healing and apposition, leading to the rapid biological fixation of implants. The different methods used for increasing surface roughness or applying osteoconductive coatings to titanium dental implants are reviewed. Surface treatments, such as titanium plasma-spraying, grit-blasting, acid-etching, anodization or calcium phosphate coatings, and their corresponding surface morphologies and properties are described. Most of these surfaces are commercially available and have proven clinical efficacy (>95% over 5 years). The precise role of surface chemistry and topography on the early events in dental implant osseointegration remain poorly understood. In addition, comparative clinical studies with different implant surfaces are rarely performed. The future of dental implantology should aim to develop surfaces with controlled and standardized topography or chemistry. This approach will be the only way to understand the interactions between proteins, cells and tissues, and implant surfaces. The local release of bone stimulating or resorptive drugs in the peri-implant region may also respond to difficult clinical situations with poor bone quality and quantity. These therapeutic strategies should ultimately enhance the osseointegration process of dental implants for their immediate loading and long-term success.     

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.     

不同粗糙表面的纯钛种植体的组织相容性评价

目的：通过将不同粗糙度的纯钛种植体植入软组织中,观察软组织对种植体的反应,评价各种种植体的组织相容性。方法：分别将光滑表面、机械表面、微粗糙表面（Ⅰ）、微粗糙表面（Ⅱ）、大粗糙表面的纯钛种植体在第1,30,60,83天分别植入家兔的背部肌肉中,在第90天切取包绕种植体的软组织,进行组织定量评价。结果：90天时微粗糙表面的种植体的软组织反应最小。结论：微粗糙表面能显著降低种植体-组织界面的炎症反应程度,减少软组织包绕层的厚度。     

Techniques for dental implant nanosurface modifications

PURPOSE

Dental implant has gained clinical success over last decade with the major drawback related to osseointegration as properties of metal (Titanium) are different from human bone. Currently implant procedures include endosseous type of dental implants with nanoscale surface characteristics. The objective of this review article is to summarize the role of nanotopography on titanium dental implant surfaces in order to improve osseointegration and various techniques that can generate nanoscale topographic features to titanium implants.

MATERIALS AND METHODS

A systematic electronic search of English language peer reviewed dental literature was performed for articles published between December 1987 to January 2012. Search was conducted in Medline, PubMed and Google scholar supplemented by hand searching of selected journals. 101 articles were assigned to full text analysis. Articles were selected according to inclusion and exclusion criterion. All articles were screened according to inclusion standard. 39 articles were included in the analysis.

RESULTS

Out of 39 studies, seven studies demonstrated that bone implant contact increases with increase in surface roughness. Five studies showed comparative evaluation of techniques producing microtopography and nanotopography. Eight studies concluded that osteoblasts preferably adhere to nano structure as compared to smooth surface. Six studies illustrated that nanotopography modify implant surface and their properties. Thirteen studies described techniques to produce nano roughness.

CONCLUSION

Modification of dental osseous implants at nanoscale level produced by various techniques can alter biological responses that may improve osseointegration and dental implant procedures.     

In vivo monitoring of the bone healing process around different titanium alloy implant surfaces placed into fresh extraction sockets

Objectives

Increasing surface roughness and coating with tricalcium phosphate of titanium and titanium alloy implants has been proposed to provide better rates of osseointegration. However, how these changes in surface topography and chemistry influence the osseointegration process of immediate implants placed in fresh extraction sockets is unclear. This study investigated the influence of three clinically employed implant surfaces on the early bone healing events in vivo.

Methods

Machined smooth implants were milled from grade 5 Ti6Al4V titanium. Surfaces were moderately roughened by grit blasting, which were then coated with tricalcium phosphate. Implants were placed into freshly extracted incisor sockets of mandibles of normal Wistar rats and left for 1, 3 and 9 weeks. Healing bone tissue around the implants was examined by histochemistry and immunocytochemistry to localise PCNA proliferative cells, and osteoblast differentiation markers osteopontin and osteocalcin. Positive synthesising cells were counted using image analysis.

Results

Histology indicated no differences in the amount or pattern of bone formation within the healing tissue surrounding the different implant surfaces. Bone healing occurred predominantly on exposed bone surfaces (distance osteogenesis) and not on the implant surface (contact osteogenesis). No differences were observed in the number or timing of PCNA, osteopontin and osteocalcin positive cells within the bone healing tissue around each of the implant analysed.

Conclusion

For immediately placed implants, the surface modifications investigated appeared to have little influence on the activity of bone forming cells surrounding the implant, probably due to the high level of distance osteogenesis seen within this scenario.

Clinical significance

For immediate placement of implants into fresh extraction sockets, titanium implants with roughened surfaces and coating with tricalcium phosphate have negligible influence in accelerating the early bone healing events of osseointegration.     

Biomechanical and histological behavior of zirconia implants: an experiment in the rat

Objective: This study aimed at evaluating the integration of zirconia implants in a rat femur model.
Material and methods: Zirconia implants with two distinct surface topographies were compared with titanium implants with similar topographies. Titanium and zirconia implants were placed into the femurs of 42 male Sprague–Dawley rats. Four groups of implants were utilized: machined zirconia implants, zirconia implants with a rough surface, machined titanium implants, and titanium implants with an electrochemically roughened surface. After a healing period of 28 days, the load-bearing capacity between the bone and the implant surface was evaluated by a push-in test. Additionally, after a healing period of 14 and 28 days, respectively, bone tissue specimens containing the implants were processed and histologically analyzed.
Results: The mean mineralized bone-to-implant contact showed the highest values after 14 and 28 days for the rough surfaces (titanium: 36%/45%; zirconia: 45%/59%). Also, the push-in test showed higher values for the textured implant surfaces, with no statistical significance between titanium (34 N) and zirconia (45.8 N).
Conclusions: Within the limits of the animal investigation presented, it was concluded that all tested zirconia and titanium implant surfaces were biocompatible and osseoconductive. The presented surface modification of zirconia implants showed no difference regarding the histological and biomechanical results compared with an established electrochemically modified titanium implant surface.     

Ultrastructural changes of smooth and rough titanium implant surfaces induced by metal and plastic periodontal probes

Objectives

To determine the ultrastructural changes of titanium surfaces of dental implants induced by the tip of periodontal probes.

Materials and methods

A total of 40 samples of smooth and rough surfaces of titanium implants were randomly assigned for the treatment with metal or plastic periodontal probes under application angles of 20° and 60°. Titanium surfaces have been evaluated with CLSM prior and following to experimental probing determining various standardized 2D and 3D roughness parameters.

Results

The average profile and surface roughness (Ra and Sa) showed no significant difference between treated and untreated samples on smooth and rough surface areas irrespective of the probe material. On smooth surfaces several amplitude roughness parameters were increased with metal probes but reached significance only for Rp (p = 0.007). Rough surface parts showed a slight but not significant reduction of roughness following to the contact with metal probes. The surface roughness remained almost unchanged on smooth and rough implant surfaces using plastic probes. The surface roughness on implant surfaces was not dependent on the application angle irrespective of the probe material.

Conclusion

Probing of titanium implants with metal probes and even less with plastic probes causes only minor changes of the surface roughness. The clinical significance of these changes remains to be elucidated.

Clinical relevance

Using plastic probes for the clinical evaluation of the peri-implant sulcus might avoid ultrastructural changes to titanium implant surfaces.

     

Removal torque and histomorphometric investigation of 4 different titanium surfaces: an experimental study in the rabbit tibia

This study presents a histomorphometric and biomechanical comparison of bone response to commercially pure titanium screws with 4 different types of surface topographies placed in the tibial metaphysis of 12 rabbits. Each rabbit had 4 implants placed, 2 in each tibia. The 4 surface topographies were a machined surface, a grit-blasted surface, a plasma-sprayed surface, and an acid-etched (Osseotite) surface. After a healing period of 5 weeks, histomorphometric and removal torque data revealed a significantly higher percentage of bone-to-implant contact and removal torque for acid-etched implants compared to machined, blasted, and plasma-sprayed implants. Within the limits of this short-term experimental study, the results indicated that micro-rough titanium surfaces obtained with acid-etching procedures achieved a 33% greater bone-to-implant contact over machined titanium surfaces with an abutment-type roughness and provided enhanced mechanical interlocking.     

不同粗糙表面的纯钛种植体与骨组织界面剪切强度的评价

目的:通过测定不同粗糙度的种植体在不同植入时间的剪切强度的变化,评价不同粗糙度种植体与骨的结合强度。方法:将纯钛的光滑试样、微粗糙表面(I)、微粗糙表面(II)、大粗糙表面等四组植入家兔股骨中,分别在术后一个月和三个月将种植体连同周围的骨组织切下来,进行拉出试验。结果:随着种植体表面粗糙度的增大,界面剪切强度呈增大。随着植入时间的增加,界面剪切强度也呈增大趋势。结论:对于纯钛,不同表面粗糙度的种植体-骨组织界面的剪切强度有明显的差异,随着粗糙度的增大,剪切强度也随之增大;随着植入时间的增加微粗糙与粗糙表面的剪切强度趋向接近。     

Underlying mechanisms at the bone-surface interface during regeneration

The goal of regenerative therapy around teeth and implants is to create a suitable environment in which the natural biological potential for functional regeneration of periodontal ligament and/or bone can be maximized. In order for the regenerative process to be successful, the following factors must be addressed: prevention of acute inflammation from bacteria, mechanical stability of the wound, creation and maintenance of blood clot-filled space, isolation of the regenerative space from undesirable competing tissue types, and the creation of a desirable surface chemistry, energy, roughness and microtopography that can directly influence cellular response, ultimately affecting the rate and quality of new tissue formation and, therefore, the regeneration process. This paper will review how surface characteristics (chemistry and roughness) can affect cell response and local factor production. To evaluate the effect of surface chemistry on cell proliferation and differentiation costochondral chondrocytes were grown on standard tissue culture plastic dishes sputter-coated with different materials. The results indicate that surface materials can elicit differential responses in cell metabolism and phenotypic expression in vitro. In a second study, the effect of varying titanium surface roughnesses on osteoblast-like cell behavior was examined. Surface roughness was found to alter osteoblast proliferation, differentiation and matrix production in vitro. In addition, production of PGE₂ and TGFβ by these cells was also shown to increase with increasing surface roughness, indicating that substrate surface roughness also affects cytokine and growth factor production. The role of surface roughness in determining cellular response was further explored by comparing the response of osteoblasts grown on new and previously used surfaces. The results of these latter studies showed that cell proliferation, expression of differentiation markers and overall matrix production are not altered when cells are grown on used vs. virgin surfaces. This suggests the possibility that implants may be re-used, especially in the same patient, if they are appropriately treated. In this context, it should also be noted that rougher titanium surfaces may require more extensive cleaning procedures. From a global perspective, these studies provide some insight into how bone regeneration can be optimized in the presence of an implant or tooth root residing at the site of a bony defect. Since the new bone being produced, during regeneration, grows from a distal area toward the implant or tooth root surface, it is hypothesized that the osteoblasts growing on the surface of the implant may produce local factors that can affect the bone healing process distally. In short, it appears that the surface characteristics of an implant, particularly roughness, may direct tissue healing and, therefore, subsequent implant success in sites of regeneration by modulating osteoblast phenotypic expression.     

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.     

不同粗糙表面的纯钛种植体表面的体外细胞培养评价

目的：本文通过对不同粗糙度表面纯钛种植体（光滑、机械表面、大粗糙表面、2种不同的微粗糙表面）的体外细胞培养评价,寻找具有较好的细胞附着的表面状态。方法：对5种不同粗糙度的钛种植体表面进行2BS成纤维细胞培养,通过光镜和电子显微镜对材料表面的成纤维细胞的数量和形态、细胞的粘附状态和细胞与种植体的关系进行了观察和分析。结果：粗糙表面的钛种植体对成纤维细胞的＂诱导能力＂更强,表现为细胞迁徙、附着于二者的细胞数目比光滑表面的钛板为多,细胞桥形成更早。结论：钛种植体表面微粗糙化提高钛材的生物相容性。     

Influence of surface roughness and shape on microdamage of the osseous surface adjacent to titanium dental implants

Objectives: To assess the relationship between smooth and roughened implant surfaces of straight and narrow configurations with respect to microdamage of the bone surface during placement of dental implants Materials and methods: Straight and tapered, rough and smooth surface Nobel Biocare implants were placed into sheep mandibles. Microdamage within the bone adjacent to the implant surface was quantitated using a semi‐automated digitized histomorphometric method. Results: Independent of implant type, microdamage, microcracks, cross‐hatch damage and diffuse damage were significantly higher close to the implants compared with far from the implants. Microcracks and cross‐hatch damage were higher for the rough cylindrical implants than all the other implant types. Conclusions: Insertion of a rough cylindrical implant type results in an increased fraction of microdamaged bone matrix in comparison to rough tapered, smooth cylindrical and smooth tapered implants. To cite this article:
Bartold PM, Kuliwaba JS, Lee V, Shah S, Marino V, Fazzalari NL. Influence of surface roughness and shape on microdamage of the osseous surface adjacent to titanium dental implants.
Clin. Oral Impl. Res. 22 , 2011; 613–618
doi: 10.1111/j.1600‐0501.2010.02024.x     

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.     

不同表面处理方法对CAD/CAM氧化锆种植体表面显微形貌的影响研究

目的：：研究采用不同表面处理方法对CAD/CAM氧化锆种植体表面显微形貌特征及粗糙度的影响。方法：通过CAD/CAM技术加工氧化锆圆盘与一段式氧化锆种植体( Y-TZP, WIELAND),根据表面处理方式分为终烧结表面、喷砂表面及喷砂加热酸蚀处理表面;标准对照组选用BEGO钛种植体表面。各组圆盘试件及种植体用扫描电子显微镜及Keyence 3D激光显微形貌测量显微镜进行表面显微形貌观察与测量。采用单因素方差分析比较各组统计学差异。结果：各组CAD/CAM氧化锆试件表面显微形貌观察显示,喷砂后表面出现边缘锐利的凹坑及沟槽;喷砂加热酸蚀处理后,氧化锆表面可见纳米级的微小孔隙及沟纹。氧化锆种植体粗糙度测量结果显示：终烧结组的表面粗糙度值(Ra=0.69μm)显著低于其他3组(P<0.001),喷砂组Ra值(Ra=1.30μm)显著低于喷砂加热酸蚀组(Ra=1.49μm)及BEGO钛种植体组(Ra=1.57μm)(P<0.01),而喷砂加热酸蚀组与BEGO钛种植体组则无显著差异(P=0.196)。结论：CAD/CAM氧化锆试件终烧结后喷砂或喷砂加热酸蚀处理均可获得较为理想的表面粗糙度,热酸蚀处理能够改变氧化锆表面的纳米级微观结构。     

种植体表面粗糙度对成骨细胞增殖及ALP含量的影响

目的:何种粗糙度的种植体能产生最快、最强的骨结合尚有争议,本研究将成骨细胞接种到不同粗糙度的钛盘表面,观察成骨细胞生长、增殖及碱性磷酸酶(alkalinephosphatase,ALP)分泌情况,探讨最适合的种植体表面粗糙度范围。方法:纯钛圆盘试件48个,分为4组,前三组喷砂加双重酸蚀粗化处理,获得表面粗糙度为(1.00±0.20)、(1.67±0.08)、(2.40±0.20)μm的三组试件。未处理的试件粗糙度为(0.12±0.03)μm,作为对照组。将成骨细胞接种到4组试件表面,观察成骨细胞形态、增殖以及ALP含量的变化,并作统计分析。结果:成骨细胞在粗糙度1.00μm的钛盘表面呈单层生长;粗糙度1.67μm的钛盘表面细胞呈立方形,有较多伪足,细胞数量及ALP含量最多;粗糙度2.40μm的试件细胞生长不规则,细胞数量及ALP含量最低。结论:粗糙的种植体表面比光滑表面更有利于成骨细胞的黏附、增殖及表达。其中粗糙度为1.00～2.40μm时成骨细胞增殖和表达最显著。