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PubMed2005

Bone tissue responses to surface-modified zirconia implants: A histomorphometric and removal torque study in the rabbit.

BACKGROUND: Zirconia ceramics are biocompatible and have mechanical properties that make them suitable as materials for dental implants. Little is known about how surface modification influences the stability and bone tissue response to zirconia implants. PURPOSE: The objective of the investigation was to histologically and biomechanically evaluate the bone tissue response to zirconia implants with two different surface modifications in comparison with machined, nonmodified zirconia implants and oxidized titanium implants. MATERIALS AND METHODS: Threaded zirconia implants with a diameter of 3.75 mm with either a machined surface (Zr-Ctr) or one of two surface modifications (Zr-A and Zr-B) were manufactured. Oxidized titanium (Ti-Ox) implants 3.75 mm in diameter were also used. The implants were characterized with regard to surface topography using an interferometer. Twelve rabbits received 96 implants using a rotational scheme, two in each tibia and two in each femur. The implants in six rabbits were subjected to removal torque (RTQ) tests after a healing period of 6 weeks. The implants in the remaining six animals were removed en bloc for light microscopic analysis. Back-scatter scanning electron microscopic (BS-SEM) analyses were used to evaluate the state of the bone-implant interface at the modified zirconia implants after RTQ testing. RESULTS: The Ti-Ox and Zr-A implants showed the highest surface roughness, followed by the Zr-B implants and, finally, the Zr-Ctr implants. The nonmodified ZrO2 implants showed statistically significant lower RTQs than all other implants. No significant differences in bone-implant contact or bone area filling the threads were observed. BS-SEM showed intact surface layers of the surface-modified implants after RTQ testing and revealed fracture of the interface bone rather than a separation. CONCLUSION: The present study showed a strong bone tissue response to surface-modified zirconia implants after 6 weeks of healing in rabbit bone. The modified zirconia implants showed a resistance to torque forces similar to that of oxidized implants and a four- to fivefold increase compared with machined zirconia implants. The findings suggest that surface-modified zirconia implants can reach firm stability in bone.

Animals↗

PubMed2003

Implant-supported titanium prostheses following augmentation procedures: a clinical report.

BACKGROUND: This report describes a novel technique for fabricating retrievable implant-supported titanium (Ti) prostheses in patients requiring a comprehensive treatment plan involving the combined efforts of maxillofacial surgery and implant prosthodontics. METHODS: Following bone graft reconstructive surgery and implant placement prosthetic treatment was initiated by inserting ITI-Octa abutments. An impression was made, and a framework was fabricated by fusing Ti-cast frameworks to prefabricated titanium copings by laser-welding. This was followed by veneering or fabrication of a removable denture with Ti metal re-enforcement. RESULTS: Favourable clinical results have been achieved using these screw-retained Ti implant-supported restorations for patients treated with reconstructive bone graft-surgery, with clinical observation periods ranging from three to four years. CONCLUSIONS: The present observations suggest that these screw-retained implant-supported Ti prostheses may be a meaningful contribution to implant prosthodontics, facilitating retrievable restorations of optimum biocompatibility, good marginal precision and with a good esthetic result. However, controlled clinical studies are needed to establish the long-term serviceability of these Ti restorations.

Adult↗

PubMed2001

Structural characterization of the metal/glass interface in bioactive glass coatings on Ti-6Al-4V.

Coating Ti-based implants with bioactive materials promotes joining between the prostheses and the bone as well as increasing long-term implant stability. In the present work, the interface between Ti-6Al-4V and bioactive silicate glass coatings, prepared using a simple enameling technique, is analyzed. High-resolution transmission electron microscopy of the glass/alloy interface shows the formation of a reaction layer ( approximately 150 nm thick) composed of Ti5Si3 nanoparticles with a size of approximately 20 nm. This nanostructured interface facilitates the formation of a stable joint between the glass coating and the alloy.

Journal Article↗

PubMed1993

Mechanical failure of hydroxyapatite-coated titanium and cobalt-chromium-molybdenum alloy implants. An animal study.

Defects in the hydroxyapatite (HA) ceramic coatings applied to metallic implant systems may occur at the time of insertion or at the time of in vivo loading. However, defects may also occur with time because of interaction with physiological fluids. A canine study was performed to make a histological and biomechanical evaluation of HA-coated titanium and cobalt-chromium-molybdenum alloy implants in a non-weight-bearing model. Twelve cylindrical plugs were inserted into the medial femoral condyle on 6 mongrel dogs. HA-coatings of 80-120 microns thickness were applied to 6 Cr-Co-Mo implants and 6 Ti-6AI-4V implants. The implants were removed together with adjacent bone tissue after 4 weeks. There were no statistically significant differences between the two groups for interface shear strength. No differences were encountered with HA-coating on Cr-Co-Mo or on Ti-6AI-4V, failure consistently being caused by disruption between the metal surface and the HA-coating, which remained fixed to the bone. At histologic evaluation the HA-coated implants exhibited a great amount of direct bone-to-implant contact. In spite of that, this study indicates that HA-coating on smooth metal surfaces might not be suitable for clinical use, because of low bonding strength between metal and coating.

Alloys↗

PubMed2006

Multifunctional Ti-(Ca,Zr)-(C,N,O,P) films for load-bearing implants.

Films of Ti-Ca-P-C-O-(N), Ti-Ca-C-O-(N) and Ti-Zr-C-O-(N) were deposited by DC magnetron sputtering or ion implantation-assisted magnetron sputtering of composite targets TiC0.5 + 10%Ca10(PO4)6(OH)2, TiC0.5 + 20%(CaO + TiO2) and TiC0.5 + 10%ZrO2 in an Ar atmosphere or reactively in a gaseous mixture of Ar + 14%N2. The microstructure, elemental and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, scanning force microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The films were characterized in terms of their hardness, Young's modulus, elastic recovery, adhesion strength, and friction and wear both in air and under physiological solution. Particular attention was paid to the analysis of deformation and fracture for various film/substrate systems during scratch testing. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments. In vitro studies involved the investigation of adhesion, spreading, and proliferation of MC3T3-E1 osteoblasts and IAR-2 epithelial cells, morphometric analysis, actin cytoskeleton, focal contacts staining, alkaline phosphatase activity and von Kossa staining of osteoblastic culture. Cell culture experiments demonstrated an increase of osteoblastic proliferation on Ca- and P-incorporated films. In vivo studies were fulfilled by subcutaneous implantation of Teflon plates coated with the tested films in mice and analysis of the population of adherent cells on their surfaces. The results obtained show that multicomponent nanostructured Ti-(Ca, Zr)-(C, N, O, P) films possess a combination of high hardness, wear resistance and adhesion strength, reduced Young's modulus, low friction coefficient and high biocompatibility.

3T3 Cells↗

PubMed2003

Patient selection for incus body coupling of a totally implantable middle ear implant.

OBJECTIVE: To evaluate audiologic selection criteria for incus body coupling (IBC) of a totally implantable middle ear implant (TI-MEI) for the treatment of sensorineural hearing loss (SNHL). MATERIAL AND METHODS: The protocol is specified in the Investigational Device Exemption of a Food and Drug Administration-approved multicenter clinical trial. The prospective study compared pre- and postoperative hearing levels using each patient as their own control. In addition, an implant on/off comparison was made. All patients had a follow-up interval of at least 6 months. Audiologic assessment tests included speech discrimination in quiet as the primary efficacy variable and pure-tone audiometry (aided thresholds), gain, speech recognition in noise and subject satisfaction using standardized questionnaires and visual analog scales (VASs) as secondary efficacy variables. The study group of patients (n = 13) was divided into 3 subgroups based on their pure-tone and speech discrimination scores: Group A consisted of 6 patients, Group B 9 patients and Group C of all 13 patients. All patients suffered from long-standing bilateral moderate to severe SNHL. Five patients were dissatisfied hearing aid (HA) users and eight subjects could not wear HAs. All patients were implanted with a TI-MEI which was coupled to the incus body. The amplification level of the device was set postoperatively using inductive digital fitting based on "most comfortable loudness" specifications. RESULTS: The implant produced median improvements from 30% (optimally fit bilateral HAs; n = 5) and 50% (HA non-users; n = 8) to 70% word recognition at 60 dB SPL. Average word recognition scores at 60, 80 and 90 dB SPL in Groups A and B showed increases from 42% (interquartile range +27%, -12%) to 93.5% (+3%, -5%) and 92.5% (+3%, -7%), respectively. In the presence of background noise, the sentence recognition threshold ranged from -2 to 1 dB signal-to-noise ratio. Maximum amplification was 50 dB at 3 kHz and 55 dB at 4 kHz. In Groups A and B, VASs revealed improvements in both natural sound impression and clarity from 62-70% of a natural sound impression to maximum scores of 100%. Using the standardized Gothenburg profile, subjective evaluations of hearing, orientation, social behavior and self-confidence reached 96-98%, 92-96% and 84-92% of the maximum score for Groups A-C, respectively. CONCLUSIONS: In selected cases, IBC of the TI-MEI investigated herein may be indicated for the treatment of SNHL, provided the following four conditions are met. First, the patient does not derive sufficient benefit from conventional HAs. Second, the specific indication for IBC is restricted to situations that do not allow the coupling of the MEI to the long incus process (e.g. due to an anatomical variation of facial nerve location). Third, IBC is restricted to patients with a steeply sloped moderate to severe high frequency SNHL, amounting to 90 dB HL from 3 to 8 kHz. Patients with low frequency SNHL should not be operated on with the IBC technique, as maximum low frequency hearing loss at 0.5 kHz must not exceed 30 dB. Fourth, Schueller's X-ray should reveal normal mastoid pneumatization. Being restricted to a 6-month follow-up period, this paper provides early clinical results and no clinical evidence of long-term efficiency of the implant.

Adult↗

PubMed2001

Evidence for a direct role of cyclo-oxygenase 2 in implant wear debris-induced osteolysis.

Aseptic loosening is a major complication of prosthetic joint surgery and is manifested as chronic inflammation, pain, and osteolysis at the bone implant interface. The osteolysis is believed to be driven by a host inflammatory response to wear debris generated from the implant. In our current study, we use a selective inhibitor (celecoxib) of cyclo-oxygenase 2 (COX-2) and mice that lack either COX-1 (COX-1-/-) or COX-2 (COX-2-/-) to show that COX-2, but not COX-1, plays an important role in wear debris-induced osteolysis. Titanium (Ti) wear debris was implanted surgically onto the calvaria of the mice. An intense inflammatory reaction and extensive bone resorption, which closely resembles that observed in patients with aseptic loosening, developed within 10 days of implantation in wild-type and COX-1-/- mice. COX-2 and prostaglandin E2 (PGE2) production increased in the calvaria and inflammatory tissue overlying it after Ti implantation. Celecoxib (25 mg/kg per day) significantly reduced the inflammation, the local PGE2 production, and osteolysis. In comparison with wild-type and COX-1-/- mice, COX-2-/- mice implanted with Ti had a significantly reduced calvarial bone resorption response, independent of the inflammatory response, and significantly fewer osteoclasts were formed from cultures of their bone marrow cells. These results provide direct evidence that COX-2 is an important mediator of wear debris-induced osteolysis and suggests that COX-2 inhibitors are potential therapeutic agents for the prevention of wear debris-induced osteolysis.

Animals↗

PubMed2005

[Experimental study on the osseointegration of nanophase hydroxyapatite biograde-coated implants].

OBJECTIVE: To study the osseointegration of the nanophase hydroxyapatite biograde-coated implants and host bone. METHODS: Nanophase hydroxyapatite biograde-coated implants, hydroxyapatite biograde-coated implants and noncoated Ti-6Al-4V implants were inserted into both femoral of Beagle canines the tissue response, dynamic osteogensis and SEM were studied at 4, 8 and 12 weeks. RESULTS: The degradation of nanophase hydroxyapatite was slower than hydroxyapatite, dynamic osteogensis and the form of osteoblast were better than the control groups. CONCLUSION: The biological reaction of Nanophase hydroxyapatite biograde-coated implants is better than hydroxyapatite coated implant.

Animals↗

PubMed2001

Bone interface of dental implants cytologically influenced by a modified sandblasted surface: a preliminary in vitro study.

To study the influences of a modified sandblasted surface (developed by the authors) on the integrating status of titanium (Ti) dental implants and bone in vitro, a three-dimensional experimental model of implant material-osteoblast culture was used. The interaction of Ti discs and osteoblasts at the interface was followed with phase-contrast microscope examination and was further observed histologically and ultra-structurally after one-month culture. Results showed that there was no significant difference between the modified sandblasted surface group and the smooth surface group in the capacity of osteoblasts migrating and attaching to Ti discs. There was, however, a significant difference in the pattern of attachment. Around the polished surface, the migrating and attaching osteoblasts oriented themselves parallel to it; however, around the modified sandblasted surface, the osteoblasts were migrating and attaching perpendicularly. There was also a major difference in the shapes of cells lining the interface; spindle-shaped on the smooth surface versus round and ovoid with a large cellular body and abundant cytoplasm on the modified sandblasted surface. Moreover, transmission electron microscopy revealed an active secretion of collagen fibrils, a bone-matrix-vesicles-mediated mineralization process, and the formation of osteocytes in the modified sandblasted surface group. Therefore, at this in vitro level, it can be concluded that the modified sandblasting surface treatment of dental implants can facilitate bone healing at their osseous interface and enable the real perpendicularly connecting bone-fiber osseointegration to form instead of the capsule-like osseous adaptation.

Cell Adhesion↗

PubMedDate not supplied

[Histologic and histomorphometric follow-up observations of osseointegration of corundum-blasted BMP-3 coated titanium test implants (Ti6Al4V) at orthotopic site in the giant rabbit].

AIM: To establish whether the additional coating of titanium implants with Bone Morphogenetic Protein-3 (BMP-3) might enhance osseous integration. METHOD: Each of 15 cylindrical titanium test implants (Ti-6AI-4V) was coated using 230 micrograms porcine BMP-3. A further 15 implants with identical (corundium-blasted) surface served as negative controls. An uncoated and a BMP-3-coated test object were implanted into the femurs of 15 adult giant rabbits. New formation of bone around the implants was examined microscopically and histomorphometrically on postoperative days 14, 35 and 56. RESULTS: Coated implants revealed superior osseointegration with statistical evaluation using the t-test for matched samples showing a significantly higher volume of new bone 5 weeks after surgery. Microscopic examination revealed osseointegration with no connective tissue membrane around the surface of the implants. CONCLUSIONS: Our results indicate that composite metal implants are suitable carriers for BMP-3 and that improved fixation of the implants can be achieved.

Alloys↗

PubMedDate not supplied

Peri-implantitis.

Peri-implant lesions are directly linked to the relationship between the implant and the soft tissue. These lesions are rare in the case of pure Ti smooth implants, but appear frequently around the rough-surfaced implants. A marginal inflammation may result in a rapid peri-implant bone loss, since the peri-implant connective tissue constitutes in a less effective barrier than the same tissue surrounding the tooth. The morphopathological examination of the peri-implant tissues revealed after their removal that the gum's mucous membrane is not inflamed, but degenerative lesions were observed both on the epithelium and chorion. The papillary lamina propria contains few cells, but it is rich in collagen fibers; vasodilatation and edema were also present. Multiple areas of lysis of the intercellular junctions were also observed at the intermediary level of the gum peri-implant epithelium (the epithelial cells undergo a process of involution at the intermediary level of the epithelium). Important changes can be seen both at the level of intercellular junction systems and at the junction between the basal extremity of the epithelial cells and the basal membrane.

Biomechanical Phenomena↗

PubMed2004

Implants coated with bioactive glass by CO2-laser, an in vivo study.

Due to ageing of the population, the number of revision operations is expected to increase. Thus good fixation of medical implants is crucial for successful treatment. In our previous studies, a method to coat titanium implants with bioactive glass (BAG) via CO2 laser treatment was introduced. It allows to localise the application of a bioactive coating, without heat treatment of the whole implant. In the present study, cylindrical titanium implants were used (BAG-coated, control group: NaOH-treated and grit-blasted Ti). Three implants were placed in each femoral epicondyle of six rabbits. After eight weeks the animals were sacrificed. Half of the implants were subjected to a torsional loading test. In the control groups, the failure occurred at the bone-implant interface, in the BAG group the failure occurred mainly in the reacted glass. The implants coated with BAG were integrated into host bone without a connective tissue capsule and were surrounded by significantly more bone than the control implants. The findings indicate clearly that the use of CO2 laser radiation to create BAG coatings did not inhibit the bioactive properties of the glass in terms of osteoconduction.

Animals↗

PubMed1993

Behaviour of titanium and titania-based ceramics in vitro and in vivo.

Cylinders, 2.8 mm in diameter and 6 mm in length which were produced from hot isostatically pressed titania (TI), titania-hydroxyapatite composite (TI/HA) and hydroxyapatite (HA) as well as commercially pure titanium (c.p. Ti), were implanted in the femurs of New Zealand white rabbits. The animals were killed at 1 and 3 months after implantation to study the development of bonding strength between the bone and the implant using the push-out test. The surface roughness and ion release of these materials in different solutions were also studied. Titania and titanium showed similar push-out strengths at 1 and 3 months after implantation. This indicates that bone has a similar response to titanium and titania due to the similarity of the surface constitute. Titania-hydroxyapatite composite showed a significant increase in bonding strength at 1 and 3 months after implantation compared with titania. A gap, < 2 microns wide, was observed by SEM at the bone-TI interface while the bone-HA interface was fully mineralized. No release of titanium ions from titania (rutile) was detected in the solutions used, including 0.1 M HCl, whilst release of titanium ions from c.p. Ti was measured in 0.02 M lactic acid and 0.1 M HCl. The results suggested that a further oxidation of titanium may improve the stability of c.p. Ti and that titania-based material may be a strong biocompatible ceramic suitable for medical applications.

Animals↗

PubMed1998

Histomorphometrical and mechanical evaluation of titanium plasma-spray-coated implants placed in the cortical bone of goats.

The aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different roughnesses. Three types of titanium plasma-spray coating were applied to beam-shaped implants: Ti2, Ti3, and Ti4, with a Ra of 16.5, 21.4, and 37.9 microm, respectively. An Al2O3 grit-blasted implant (Ti-un) with a Ra of 4.7 microm was used as a control. In total, 72 implants were inserted in the tibial cortical bone of nine adult female goats. These implants were evaluated histologically and mechanically 3 months after implantation. At the end of the experiment, of the 72 inserted implants, two implants (one Ti2 and one Ti4) were lost. Histological evaluation of the other retrieved implants revealed a uniform bone reaction for all implants. The unloaded plasma-spray coatings showed no signs of delamination at the implant-coating interface. Occasionally, particles of the Ti4 coating broke free and were found near the implant. Histomorphometry revealed no difference in bone contact for the different implants (P > 0.05). Furthermore, the push-out test showed no significant difference (P > 0.05). Linear regression showed no interaction between the push-out values and the roughness values (r = 0.5). On the basis of these results, it may be concluded that the used surface roughnesses did not lead to differences in bone response or mechanical attachment strength in goat cortical bone.

Animals↗

PubMed2006

Photocoupling of fibronectin to titanium surfaces influences keratinocyte adhesion, pellicle formation and thrombogenicity.

OBJECTIVES: Coating of implant surfaces with biomolecules can influence basic host responses and enhance subsequent tissue integration. The biological factors have to be immobilized on the implant material. Human fibronectin (Fn) was used as a model protein and covalently coupled to titanium (Ti) surfaces via silanization and an anthraquinone linker. The impact on several aspects of initial host/biomaterial interactions (keratinocyte adhesion, platelet interactions and pellicle formation) was studied. METHODS: Coupling efficiency was characterized by immunological techniques. The effects of coupled Fn on initial host/biomaterial interactions were assessed. Cell adhesion and spreading were investigated by fluorescent staining, pellicle formation by an acoustic sensor system (quartz crystal microbalance with dissipation, QCM-D), and platelet adhesion as one parameter mediating the inflammatory response by scanning electron microscopy (SEM) and immunological assays. RESULTS: Coupling efficiency was related to irradiation time used for photochemical coupling of the UV-activated anthraquinone to the silanized Ti surface. With an optimized protocol, the amount of Fn coupled to the surface could be almost doubled compared to standard dip-coating methods. On the anthraquinone-coupled Fn coatings, cell adhesion and spreading of human keratinocytes was significantly enhanced. Online detection of pellicle formation revealed strong reversibility of saliva protein adhesion on Fn coated surfaces compared to the pure Ti surface. Furthermore, the Fn coated Ti showed a low thrombogenicity. SIGNIFICANCE: This study suggests that anthraquinone-coupled biological coatings may be useful for biofunctionalization of Ti dental implants by enhancement of soft tissue re-integration (restoration of the epithelial seal) combined with diminished pellicle formation.

Anthraquinones↗

PubMed2006

Osseointegration and mechanical stability of pyrocarbon and titanium hand implants in a load-bearing in vivo model for small joint arthroplasty.

PURPOSE: To test the mechanical stability and histologic osseointegration under load-bearing conditions of 2 different materials, pyrocarbon (Py) and titanium (Ti), in a rabbit model. METHODS: Proximal interphalangeal implants (9 Ti, 8 Py) were placed into rabbit knees and the animals were killed after 3 months. Subsidence was assessed by monthly x-rays. Mechanical stability was measured with a nondestructive pullout test. Implant osseointegration was evaluated by an analysis of the relative implant-calcified bone contact surface on microradiographs and by a histomorphometric analysis of the percentage of bone and connective tissue contact with the implant surface. Histologic examination included assessment of bone apposition on the basis of fluorochromes. RESULTS: Subsidence was found in all 8 Py implants but in none of the Ti group. All 9 Ti implants were mechanically stable; all 8 Py implants were loose. A significantly higher implant-bone contact was found for the Ti group compared with the Py group. Bone apposition increased with time and was highest for the Ti implants 6 weeks after implantation. CONCLUSIONS: In the rabbit model osseointegration of implants was highly dependent on the material. A reliable osseointegration was found for Ti implants. For Py implants no osseointegration or implant stability was achieved. For use of small joints of the hand we therefore recommend Ti-based implants.

Animals↗

PubMed1991

Fixation of titanium and hydroxyapatite-coated implants in arthritic osteopenic bone.

Retrieval studies of porous-coated prostheses have demonstrated deficient bony ingrowth in high percentages. Possible reasons for this are lack of initial mechanical stability and the presence of osteopenia. The authors studied ingrowth of osteopenic bone into titanium alloy (Ti) porous-coated implants with and without hydroxyapatite (HA) coating in an experimental dog model. Unilateral osteopenia of the knee with a 20% reduced bone density as judged by computed tomography (CT) scanning (P less than .001) was induced in 12 mature dogs by weekly intraarticular injections of Carragheenin into the right knee for 12 weeks, with the left knee serving as control. Ti porous-coated cylinders were inserted in press-fit bilaterally in the lateral femoral condyles in six dogs. HA-coated titanium plugs were implanted similarly in another sex-, age-, and weight-matched group of six dogs. Bony ingrowth after 4 weeks was significantly reduced for Ti implants in osteopenic bone compared to control bone, but HA-coated implants were covered by equal amounts of bone tissue. Bone-implant shear strength of Ti implants also was reduced in osteopenic bone compared to control bone. In control bone, the anchorage of Ti implants was stronger than HA-coated implants, whereas the fixation of Ti and HA-coated implants was equal in the osteopenic bone. The results demonstrate that the bony fixation of Ti porous-coated implants is weakened by the presence of experimentally induced osteopenia. However, the fixation of HA-coated implants was not affected by the osteopenic condition in the surrounding bone. The fixation of Ti and HA-coated implants was equal in osteopenic bone, whereas the fixation of Ti porous-coated implants was superior to that of HA-coated implants in control bone.

Animals↗

PubMed1992

Bone graft incorporation around titanium-alloy- and hydroxyapatite-coated implants in dogs.

To evaluate cancellous allogenic bone graft incorporation into porous-coated implants, the fixation of titanium alloy-(Ti) and hydroxyapatite-(HA) coated implants with and without bone graft was compared. An unloaded model with unilateral carragheenin-induced osteopenia of the knee was used in 12 mature dogs. Ti- and HA-coated cylinders were implanted in the distal femoral condyles and centralized in 2-mm overreamed drill holes. Allogenic, fresh-frozen (-80 degrees) cancellous bone graft was packed around the implants in six dogs. In a matched group of six other dogs, the implants were left in overreamed canals without bone graft. After six weeks the interface shear strength of grafted Ti-coated implants had significantly increased compared to the nongrafted Ti implants. However, HA coating used without bone graft was capable of enhancing the bone-implant interface shear strength to nearly the same degree. The fixation of grafted Ti- and HA-coated implants was equal. No significant difference in implant fixation was found between osteopenic and control bone. Histomorphometric evaluation of mineralizing surfaces in direct contact with the implant confirmed the results from the push-out test. Bone-implant fixation when using allogeneic fresh-frozen cancellous bone graft in osteopenic and control bone was enhanced by hydroxyapatite coating but the HA coating alone appeared to offer almost the same improvement in anchorage in 2-mm defects. Loss of bone stock around loose prosthetic implants often requires bone grafting. However, because of anatomic constraints in joint prosthetic surgery, a complete filling of defects with bone graft is difficult, and areas of gaps between bone and implant will remain. Provided mechanical stability of the prosthesis, the results reported here suggest that these areas will probably be filled early with new mineralizing bone if the prosthesis is coated with a thin layer of hydroxyapatite.

Animals↗