电解液Ca,P浓度对纯钛表面微弧氧化膜结构和特性的影响

目的:研究电解液不同Ca,P浓度对纯钛表面微弧氧化膜结构和特性的影响.方法:根据电解液中Ca,P浓度的不同,将纯钛试件分成A,B和C共3组,通过微弧氧化技术制备纯钛表面氧化膜,D组作对照组.使用扫描电镜(SEM)检测氧化膜的表面及横断面形貌,用X射线能谱仪(EDS)检测氧化膜的元素成分,用X射线衍射仪((XRD)检测氧...     

Early bone tissue responses to turned and oxidized implants in the rabbit tibia

Background: Previous studies have shown the formation of more bone contacts with a moderately rough and porous titanium surface, created by anodic oxidation, as compared with nonmodified turned titanium control surfaces. The mechanisms leading to a stronger bone response to oxidized titanium are not well understood.
Purpose: The aim of the study was to describe the early events of bone integration of titanium implants with oxidized and turned surfaces.
Materials and Methods: Nine adult New Zealand White rabbits and 18 implants were used in the study. One oxidized and one turned threaded titanium implants, which had been placed in the right tibial metaphysis, were analyzed in the present study. The implants were retrieved after 7, 14, and 28 days for light microscopic examination and histomorphometric measurements in ground sections.
Results: Integration of oxidized implants was seen to occur as direct bone formation on the surface, while the integration of turned implants was a result of bone ingrowth from preexisting bone and bone marrow. For oxidized implants, an almost acellular, darkly stained layer was seen after 7 to 14 days, which later became populated with osteoblasts. The presence of osteoid seams indicated appositional bone growth from the substrate toward the surrounding tissues. The bone contact values were higher for oxidized implants, and the bone area values were higher for turned implants.
Conclusions: The present study confirms the idea that implant surface modification alters the bone tissue response to titanium. The early bone formation following surgery occurs directly on the moderately rough oxidized surface, while turned titanium surfaces are integrated by the ingrowth of bone from the adjacent bone marrow and preexisting bone tissues.     

BMP stimulation of bone response adjacent to titanium implants in vivo

The objective of this study was to evaluate the effect of bone morphogenetic protein (BMP) on the bond strength of titanium (Ti) implants at the bon-implant interface. Thirty-six Brånemark screw implants (3.75 mm diameter by 15 mm long) were implanted for 3 and 12 weeks. At 3 weeks after implantation, the mean reverse torque value for implants stimulated with BMP delivered using an atelopeptide type-1 collagen carrier (74.2±5.2 N cm) was observed to be statistically greater (P<0.000016) than the mean reverse torque value for control Ti implants (32.8±1.1 N cm). Similarly, at 12 weeks after implantation, the mean reverse torque value for implants stimulated with BMP (89.2±2.7 N cm) was statistically greater (P<0.0042) than the mean reverse torque value for control Ti implants (75.8±2.4 N cm). In addition, hisiomorphometric evaluations indicated more bone contact with the BMP stimulated implant surfaces compared to the controls after 3 weeks implantation. It was concluded from this study that the use of BMP-atelopeptide type-1 collagen mixture is an effective means of obtaining greater bond strength at the bone-implant interface within a shorter time period than Ti implants without BMP.     

Oxidized, bioactive implants are rapidly and strongly integrated in bone. Part 1--experimental implants

OBJECTIVES: The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants. MATERIAL AND METHODS: Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed. RESULTS: The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone. CONCLUSIONS: Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.     

Enhanced osteoconductivity of micro-structured titanium implants (XiVE S CELLplus™) by addition of surface calcium chemistry: a histomorphometric study in the rabbit femur

Objectives: This study evaluated the osseointegration in rabbit cancellous bone of titanium (Ti) implants with a micro-topographically complex surface structure produced by grit-blasting/acid-etching with or without the addition of surface calcium ion (Ca) chemistry.
Material and methods: Micro-structured Ti implants (XiVE S CELLplus^™ screw implant, Dentsply Friadent GmbH) were hydrothermally treated in an alkaline Ca-containing solution to produce a nano-structured Ca-incorporated oxide surface layer. The surface characteristics were evaluated by scanning electron microscopy and stylus profilometry before and after Ca surface treatment. Twenty implants (10 control and 10 experimental) were placed in the femoral condyles of 10 New Zealand White rabbits. Histomorphometric analysis was performed 6 weeks after implantation.
Results: Ca-incorporated and untreated control implants showed similar surface morphologies and surface roughness values at the micron scale. Untreated micro-structured Ti implants achieved a high degree of bone-to-implant contact (BIC), and Ca incorporation further increased BIC% ( P <0.05). Active new bone apposition was found on surfaces of Ca-incorporated implants in areas of loose trabeculae.
Conclusion: The nano-structured Ca-incorporated oxide surface significantly enhanced osteoconductivity of micro-structured Ti implants in rabbit cancellous bone. Results indicate that this surface produced by simple hydrothermal treatment may be effective in improving the osseointegration of implants with micro-topographically complex surface structures in areas of loose cancellous bone.     

钛种植体与骨界面的三维结构分析

本研究对植入猴下颌骨３个月的纯钛螺旋状种植体与骨的界面结构形态进行了定性和定量分析，采用计算机对唇颊面以７５μｍ间隔的系列磨片进行分析和综合，结果得到直观的种植体与骨界面各部位形态的计算机图像，同时获得种植体周围各部位的骨接触率。在所考察的三个种植体中，唇侧和上部均有较高的骨接触率，三个种植体全表面的骨接触率分别为３８％，５０％和５２％。     

Bone-implant contact at calcium phosphate-coated and porous titanium oxide (TiUnite)-modified oral implants

BACKGROUND: Calcium phosphate (CP)-coated implants are usually referred to as having osteoconductive properties, whereas titanium implants with a native oxide layer are considered less osteoconductive. Often smooth titanium oxides (TOs) are compared to relatively rough CP structures. The objective of this study was to evaluate osteoconduction by comparing bone-implant contact at a relatively smooth, highly crystalline CP coating with a structured, porous TO (TiUnite)-modified surface. MATERIAL AND METHODS: Ten adult Hound Labrador mongrel dogs were used. Four titanium implants (Nobel Biocare) with CP-coated (2) or TO-modified (2) surfaces were installed 12 weeks following mandibular premolar and molar teeth extraction. The implants were alternated within and between jaw quadrants in consecutive animals. Mucosal flaps were advanced and sutured leaving the implants in a submerged position. The animals were injected with fluorescent bone labels at 3 and 4 weeks postsurgery, and pre-euthanasia to monitor progress of bone formation. The animals were euthanized at 8 weeks postsurgery and block biopsies were prepared for histologic and histometric analysis. RESULTS: There were no remarkable differences in bone formation and apparent bone-implant contact comparing the TO-modified and CP-coated surfaces. However, the measured average bone-implant contact was 71% and 57% (P=0.027) for TO-modified and CP-coated implants, respectively. CONCLUSIONS: We conclude that the TO surface exhibits osteoconductive properties exceeding that of the CP surface. One or several of the chemical and physical properties of the TO surface may result in the remarkable bone formation along its surface. This study indicated that crystallinity and/or chemistry may be important.     

Tissue response to titanium implantation in the rat maxilla, with special reference to the effects of surface conditions on bone formation

Tissue responses to titanium implantation with two different surface conditions in our established implantation model in rat maxillae were investigated by light and transmission electron microscopy and by histochemistry for tartrate-resistant acid phosphatase (TRAPase) activity. Here we used two types of implants with different surface qualities: titanium implants sandblasted with Al2O3 (SA-group) and implants coated with hydroxyapatite (HA-group). In both groups, bone formation had begun by 5 days postimplantation when the inflammatory reaction had almost disappeared in the prepared bone cavity. In the SA-group, however, the bone formation process in the bone cavity was almost identical to that shown in our previous report using smooth surfaced implants (Futami et al. 2000): new bone formation, which occurred from the pre-existing bone toward the implant, was preceded by active bone resorption in the lateral area with a narrow gap, but not so in the base area with a wide gap. In the HA-group, direct bone formation from the implant toward the pre-existing bone was recognizable in both lateral and base areas. Many TRAPase-reactive cells were found near the implant surface. On the pre-existing bone, new bone formation occurred with bone resorption by typical osteoclasts. Osseointegration around the implants was achieved by postoperative day 28 in both SA- and HA-groups except for the lateral area, where the implant had been installed close to the cavity margin. These findings indicate that ossification around the titanium implants progresses in different patterns, probably dependent on surface properties and quality.     

Evaluations of bone tissue integration to pure and alloyed titanium implants

Purpose: This study was performed for comparisons of tissue integration to commercially pure (CP) and titanium-6-aluminum-4 vanadium (Ti-6-Al-4V) implants using various existing three-dimensional biomechanical and two-dimensional histomorphometrical techniques, and to monitor the loosening torque during in vivo removal torque (RTQ) test with a novel unit not used before in a pilot study in rabbits.
Materials and Methods: The implants were topographically characterized and inserted in femurs and tibiae of five rabbits (in total 40 implants, 20 per group). After 16 weeks, the implant integration was biomechanically evaluated by: (1) resonance frequency test, and (2) peak RTQ test and the graph from the monitoring curve. Biopsies of the implants in situ were processed to undecalcified cut and ground sections followed by light microscopical quantifications. Shear strength calculations were performed.
Results: Significantly higher mean value of RTQ ( p  = .01) and shear strength tests ( p  = .03) were observed for the CP titanium implants compared to Ti-6-Al-4V implants. The monitoring curve from the RTQ test demonstrated no differences in the shape or form that could provide further information about the differences in the implant-to-bone attachment.
Conclusions: The CP titanium implants showed increased RTQ and shear strength values compared to the Ti-6-Al-4V implants. The new tool of monitoring the RTQ curve could not demonstrate differences between the two materials. The exact influence of the implant materials on the surrounding tissues needs to be further investigated.     

Effect of surface roughness and calcium phosphate coating on the implant/bone response

The influence of surface roughness and calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated. Four types of titanium implants, i.e. as-machined, grit blasted, as-machined with Ca-P sputter coating, and grit blasted with Ca-P sputter coating, were prepared. The Ca-P sputter-coating, produced by using the RF magnetron sputter technique, was rapid heat-treated with infrared radiation at 600 degrees C. These implants were inserted into the left and right femoral condyles and the left and right tibial diaphyses of the rabbits. After implantation periods of 2 and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. Histological evaluation revealed no new bone formation around different implant materials after 2 weeks of implantation. After 12 weeks, bone healing was almost completed. For both tibial and femoral implants, Ca-P coated implants always showed a higher amount of bone contact than either of the non-coated implants. On the other hand, surface roughness improved only the response to implants inserted into the tibial diaphysis. On the basis of these findings, we concluded that 1) deposition of a sputtered Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase, and 2) besides implant surface conditions the bone response is also determined by local implant site conditions.     

Bone response adjacent to calcium phosphate electrostatic spray deposition coated implants: an experimental study in goats

BACKGROUND: A new technique to deposit calcium phosphate (CaP) coatings onto titanium substrates has been developed recently. This electrostatic spray deposition (ESD) technique seems to be very promising. It appears to have clinical advantages such as an inexpensive and simple set-up, high deposition efficiency and the possibility to synthesize layers with a defined surface morphology. OBJECTIVE: The aim of this study was to examine biological properties and osteoconductivity of ESD CaP coatings when inserted into the femoral condyle of a goat. MATERIAL AND METHODS: Twenty-four implants with two gaps, i.e. 1 or 2 mm, were inserted into the femoral condyles of six goats. The implants were coated on one side with either a commercially available plasma-sprayed hydroxyapatite (HAPS) coating or an ESD carbonate apatite (CAESD) coating. The other side of the implant was always left uncoated (Ti). Twelve weeks after implantation the animals were sacrificed and the characteristics of bone ingrowth and bone contact were evaluated. Results: At 3 months, histological and quantitative histomorphometrical measurements demonstrated more bone ingrowth and bone contact for coated sites as compared with uncoated sites. Statistical testing revealed that for both the 1 and 2 mm gaps HAPS (plasma-sprayed hydroxyapatite) as well as CAESD (ESD carbonate apatite) -coated surfaces always had a significantly higher (P<0.05) amount of bone contact than uncoated Ti surfaces. On HAPS surfaces always significantly more bone was present than on CAESD surfaces. Further statistical testing revealed a significant difference in bone ingrowth between the HAPS as well as CAESD and Ti 1+2 mm gap specimens (P<0.05). Further, HAPS 1 mm gaps showed more bone ingrowth than CAESD 1 mm gaps. No significant difference existed between HAPS and CAESD 2 mm gaps. CONCLUSION: On the basis of our observations, we conclude that the used ESD technique is a promising new method to deposit CaP coatings onto titanium substrates. On the other hand, plasma-spray HA-coated implants have a still more favourable effect on the bone response.     

Bone marrow mesenchymal stem cell response to nano-structured oxidized and turned titanium surfaces

Objectives: The aim of this study was to analyse the topographic features of a novel nano‐structured oxidized titanium implant surface and to evaluate its effect on the response of human bone marrow mesenchymal stem cells (BM‐MSC) compared with a traditional turned surface. Methods: The 10 × 10 × 1 mm turned (control) and oxidized (test) titanium samples (P.H.I. s.r.l.) were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and characterized by height, spatial and hybrid roughness parameters at different dimensional ranges of analysis. Primary cultures of BM‐MSC were seeded on titanium samples and cell morphology, adhesion, proliferation and osteogenic differentiation, in terms of alkaline phosphatase activity, osteocalcin synthesis and extracellular matrix mineralization, were evaluated. Results: At SEM and AFM analyses turned samples were grooved, whereas oxidized surfaces showed a more complex micro‐ and nano‐scaled texture, with higher values of roughness parameters. Cell adhesion and osteogenic parameters were greater on oxidized (P<0.05 at least) vs. turned surfaces, whereas the cell proliferation rate was similar on both samples. 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, spatial and, mostly, of hybrid parameters. This different micro‐ and nano‐structure resulted in an enhanced adhesion and differentiation of cells plated onto the oxidized surfaces.     

Bone reactions adjacent to titanium implants with different surface characteristics subjected to static load. A study in the dog (II)

The purpose of the present study was to compare bone reactions adjacent to titanium implants with either a titanium plasma-sprayed (TPS) or a machined surface subjected to lateral static loading induced by an expansion force. In 3 labrador dogs, the 2nd, 3rd and 4th mandibular premolars were extracted bilaterally. 12 weeks later, 2 implants with a TPS surface were placed in one side and 2 implants with a machined surface were placed in the contralateral side. Twelve weeks after implant installation, crowns, connected in pairs with orthodontic expansion screws, were fitted to the implants and a 0.6 mm wide expansion was initiated. Clinical registrations, standardized radiographs and fluorochrome labeling were carried out during a 24-week period of loading. Biopsies with the implants in situ were harvested and processed for ground sectioning. The sections were subjected to histologic and histometric examination. A higher marginal bone level was observed around implants with a TPS surface compared to machined implants. Furthermore, the values describing the amount of bone-to-implant contact at the bone/implant interface as well as the density of the peri-implant bone were lower at the machined than at the TPS implants.     

The effect of micro-motion on the tissue response around immediately loaded roughened titanium implants in the rabbit

Initial osteogenesis at the implant interface is, to a great extent, determined by the implant surface characteristics and the interfacial loading conditions. The present study investigated the effect of various degrees of relative movement on the tissue differentiation around a roughened screw-shaped immediately loaded implant. Repeated-sampling bone chambers were installed in the tibia of 10 rabbits. In each of the chambers, three experiments were performed by inducing 0 (control), 30, and 90 microm implant displacement for 9 wk. A linear mixed model and a logistic mixed model with alpha = 5% determined statistical significance. Tissue filling of the bone chamber was similar for the three test conditions. The bone area fraction was significantly higher for 90 microm implant displacement compared with no displacement. A significantly higher fraction of bone trabeculae was found for 30 and 90 microm implant displacement compared with the unloaded situation. The incidence of osteoid-to-implant and bone-to-implant contact was significantly higher for 90 microm implant displacement compared with 30 and 0 microm implant displacement. Significantly more osteoid in contact with the implant was found for the loaded conditions compared with no loading. Well-controlled micro-motion positively influenced bone formation at the interface of a roughened implant. An improved bone reaction was detected with increasing micro-motion.     

The effect of hyperbaric oxygen treatment on bone tissue reactions to c.p. titanium implants placed in free autogenous bone grafts. A histomorphometric study in the rabbit mandible.

This study aimed to investigate the effect of hyperbaric oxygen (HBO) therapy on the tissue reactions to commercially pure (c.p.) titanium implants placed in free autogenous bone graft by a 1-stage procedure. Eighty c.p. titanium implants were placed in the bone grafted from iliac crest to bilateral mandible of 40 Japanese white rabbits without tapping. Twenty rabbits underwent daily a HBO treatment for 60 min under 2.4 ATA during 20 consecutive days and the other untreated 20 rabbits served as controls. The implants with surrounding bone tissue were retrieved 20, 30, 60, 90 and 120 days after surgery, fixated, dehydrated and embedded in resin. About 20 microns thick ground sections were prepared prior to microscopical observations. The bone area and the bone-to-implant contact inside the threads were calculated separately in the grafted bone and in the host bone for each implant. After 30 and up to 120 days, the HBO treated group showed more bone-to-implant contacts in the grafted bone as compared to the non-HBO treated group. In the host bone there were no differences observed between HBO and non-HBO treated groups. This study indicated that HBO treatment was beneficial for the tissue incorporation of c.p. titanium implants when placed immediately in free autogenous bone grafts.