Structural aspects of the interface between tissue and titanium implants.
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Animals↗
Biomedical subjects
T Albrektsson
Publications and source records attributed to T Albrektsson.
Direct bone anchorage of external hearing aids.
Some patients with hearing disorders cannot wear a conventional hearing aid but have to use bone conduction in which the aid has to be attached with steel springs over the head. A new method of reconstruction involving the insertion of bone-anchored screws has been tested in a clinical survey of 14 patients. A titanium implant was anchored in the temporal bone and, in a later session, connected to a skin penetrating abutment. An external hearing aid was snapped on to the abutment. The patients have now been followed up for 53 months. There have been no problems with the bone anchorage or with infections around the skin penetration site. The hearing of the patients has improved. The cosmetic result is reported to be favourable.
Adolescent↗
Osseointegrated titanium fixtures in the treatment of edentulousness.
A 91 per cent positive 5-9 year result has been reported when using titanium implants and gold bridges to restore edentulous jaws. About 400 consecutive patients have been operated. The reasons for the good results are believed to depend on the anchorage of the implants in the living bone without interposing soft tissue layers. Repeated X-rays ensuring a strict parallelism are used to indicate direct bone integration. Some implants had to be removed in spite of still being anchored in the bone. In these cases SEM and TEM provided direct evidence of an osseointegration.
Dental Implantation↗
Directly bone-anchored implants for fixation of aural epistheses.
In cases of missing outer ears, generally, epistheses are attached to eye-glasses which gives insecure attachment and a fairly poor cosmetic result. A new method for stable episthesis attachment is being tested in Gothenburg, Sweden. Threaded, cylindrical titanium implants are inserted with a meticulous technique in the temporal bone of the patient. At the next stage, 3-4 months later, the implants are connected to abutments which are allowed to penetrate the skin. To these abutments a silicone episthesis is attached. Presently, 7 patients who had no outer ear because of congenital disorders, hereditary diseases or status post trauma or tumour surgery have been operated and followed for up to 3 1/2 years. There have been no problems reported with the bone anchorage or the skin penetration.
Adult↗
Electron microscopic analysis of the bone-titanium interface.
Ten cylindrical implants, made of polycarbonate and covered with a 120-250-nm-thick layer of pure titanium, were implanted into each tibial metaphysis of five rabbits. Observation time was 12 weeks. The implants were surrounded by mature, living bone. No soft tissue intervened between bone and implant at any point. With TEM microscopy the titanium was shown to be bordered by a 20-nm-thick layer of proteoglycans, showing the characteristics of ground substance, and separating the collagen from the implant surface. Cells at the interface were likewise separated from the titanium by such a layer. Hydroxyapatite crystals were observed within the ground substance layer, occasionally seemingly in direct contact with the titanium. Normal mineralization was present 100-500 nm from the implant surface. While this study aims at defining interface anatomy, it also shows that macroscopically smooth-surfaced titanium can readily heal into bone without a soft tissue envelope. This could be of help for materials' choice and design of permanently fixed implants.
Animals↗
Thermal injury to bone. A vital-microscopic description of heat effects.
A titanium implant, the thermal chamber, allowing vital microscopic observations of bone tissue during heating and bone temperature measurements to be made simultaneously is described. The tissue reactions to a defined heat trauma may be followed and registered on slides and ciné film. The thermal chamber technique allows repeated observations of the same bone tissue compartment for indefinite follow-up period. In the present experiment, the chamber was inserted in the rabbit tibia and heating to 53 degrees C was applied for 1 min. During heating to the assigned temperature, the blood-flow velocity initially increased. At 53 degrees C the blood flow stopped in some vessels and became sluggish in others. 2 days after heating the blood flow in the pre-existing vessels had stopped. Gradually thereafter, all original vessels became replaced with ingrowing newly-developed vascular pathways. Fat cells seen before burning became resorbed and bone remodelling started 3-5 weeks after the heat injury. A temperature of 53 degrees C, i.e. below the denaturation point of alkaline phosphatase, caused an irreversible bone injury, after which healing occurred from the surrounding tissues.
Animals↗
Titanium implants permanently penetrating human skin.
Titanium implants were allowed to penetrate the skin of the upper arm of 8 human volunteers in an attempt to investigate the conditions for a permanent implant transcutaneous passage. If a construction was used that restricted the skin movements around the implant no inflammatory or other adverse soft tissue effects were noted for follow-up periods of 7-25 months. In another clinical investigation of 4 patients with hearing impairment, titanium implants were firmly anchored in the temporal bone, allowed to penetrate the skin and external hearing aids were directly attached. These transcutaneous implants are still functioning without any problems at a follow-up period of 38-50 months. The reason for the favorable results achieved are thought to be connected to the material (non-alloyed titanium), the design of the implant and a minimally traumatising surgery. The results of this paper are pointing to new treatment possibilities using external prostheses anchored to the skeleton via skin penetrating mechanical connections as e.g. stable and permanent episthesis attachment in cases of severe facial injuries. A clinical trial along these lines is presently being performed.
Adult↗
Fibrin adhesive system (FAS) influence on bone healing rate: a microradiographical evaluation using the bone growth chamber.
A dividable titanium implant containing two canals was inserted into both tibial metaphyses of 5 adult rabbits to test whether the Fibrin Adhesive System (FAS) can accelerate bone regeneration. On one side the implants were pretreated with FAS whereas the implants on the contralateral side were bathed in autologous blood and marrow. After a healing time of 4-5 weeks the assembled implants were removed and then taken apart. The amount of bone which had grown into the canals was quantified by microradiography and microdensitometry. The FAS-treated implants showed a tendency to contain less bone than the medullary cell-treated ones. It is concluded that more evidence should be gathered before recommending FAS treatment to accelerate bone regeneration. It is submitted in addition that the dividable titanium implant, the Bone Growth Chamber, may be useful for quantification of early bone formation under various experimental conditions.
Absorptiometry, Photon↗
[Permanent denture implantation. A new Swedish biotechnological rehabilitation method].
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Dental Implantation, Endosseous↗
Indirect and direct methods to study bone tissue. New possibilities with the titanium chamber.
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Animals↗
Intravital, long-term follow-up of autologous experimental bone grafts.
Using a vital microscopic method, it has been possible to follow the vascular changes and bone remodelling in the same bone graft from the time of transplantation till one year afterwards. Grafts which received their first vessel early (5-9 days after grafting) contained vital bone and a vivid blood circulation one year after transplantation. Grafts which received their first vessel late (17-29 days after grafting) were only partly revascularized after one year and contained islands of dead bone. Minimal surgical trauma to both graft and the host bed is important for early revascularization of the graft, and, therefore, also contributes to a more complete incorporation of the graft.
Animals↗
Mandibular reconstruction using the preformed autologous bone graft.
Preformed bone grafts (PBG) were inserted in large jaw bone defects in 5 patients. The grafts in all cases healed-in rapidly. Two patients died of metastatic sarcoma 1 year after grafting. The other patients are healthy with excellently functioning grafts 3, 5 and 8 years after transplantation, respectively. The preformation of bone grafts is, however, regarded as a resource consuming technique that should be used only in selected cases of mandibular reconstruction. Particularly in young individuals, the better results achieved with PBG, in comparison with other types of grafts, seem to justify the more complicated surgical procedure. Apart from a description of the preformation technique, the present paper also introduces advice as how to minimally traumatize the hard tissues in bone graft surgery.
Adult↗
Osseointegrated titanium implants. Requirements for ensuring a long-lasting, direct bone-to-implant anchorage in man.
A total of 2895 threaded, cylindrical titanium implants have been inserted into the mandible or the maxilla and 124 similar implants have been installed in the tibial, temporal or iliac bones in man for various bone restorative procedures. The titanium screws were implanted without the use of cement, using a meticulous technique aiming at osseointegration--a direct contact between living bone and implant. Thirty-eight stable and integrated screws were removed for various reasons from 18 patients. The interface zone between bone and implant was investigated using X-rays, SEM, TEM and histology. The SEM study showed a very close spatial relationship between titanium and bone. The pattern of the anchorage of collagen filaments to titanium appeared to be similar to that of Sharpey's fibres to bone. No wear products were seen in the bone or soft tissues in spite of implant loading times up to 90 months. The soft tissues were also closely adhered to the titanium implant, thereby forming a biological seal, preventing microorganism infiltration along the implant. The implants in many cases had been allowed to permanently penetrate the gingiva and skin. This caused no adverse tissue effects. An intact bone-implant interface was analyzed by TEM, revealing a direct bone-to-implant interface contact also at the electron microscopic level, thereby suggesting the possibility of a direct chemical bonding between bone and titanium. It is concluded that the technique of osseointegration is a reliable type of cement-free bone anchorage for permanent prosthetic tissue substitutes. At present, this technique is being tried in clinical joint reconstruction. In order to achieve and to maintain such a direct contact between living bone and implant, threaded, unalloyed titanium screws of defined finish and geometry were inserted using a delicate surgical technique and were allowed to heal in situ, without loading, for a period of at least 3--4 months.
Adult↗
Osseointegrated titanium implants in the temporal bone. A clinical study on bone-anchored hearing aids.
The purpose of this study is to investigate the possibilities for attaching a new type of direct bone conduction hearing aid. Using a gentle surgical technique, titanium screws were inserted into the temporal bone of fourteen patients suffering from hearing impairment. The implants became integrated with the living bone tissue and have remained so for a follow-up period of, at present, two to four years. It is therefore concluded that titanium implants may be osseointegrated in the temporal bone in a similar manner to that previously described for long bones. The bone-anchored titanium screws were connected to a permanently skin-penetrating abutment, which in turn was used for attachment to a hearing aid. In this way a direct bone conduction without obstructing soft tissue layers is secured. The permanent skin penetration caused no adverse soft tissue effects. The new system has improved pure-tone hearing threshold by about 15 dB. Further research is aimed at the construction of a new hearing aid that is better adapted to the impedance situation existing in the directly bone-anchored cases.
Adolescent↗
A method for short- and long-term in vivo study of the bone-implant interface.
A screw-shaped titanium chamber has been designed for serial in vivo observations of the bone-implant interface. First, the chamber is implanted; later a test substance, e.g. bone cement, is inserted in the chamber and brought in contact with the bone with minimal trauma. Both acute and long-term effects can be intravitally observed, photographed, and recorded.
Animals↗
Microangiographic representation of the microvascular system in bone tissue: a vital microscopic evaluation in the rabbit.
A titanium chamber, enabling in situ studies of living bone, was inserted into the adult rabbit metaphysis. The true vascular state of an observable bone tissue compartment was microscopically defined after autologous grafting of the chamber and a surrounding bone collar. Micropaque and India ink microangiography, respectively, were performed under direct, simultaneous inspection in a vital microscope. In 20 animals Micropaque and India ink, on the average, filled out less than 50% of the actually functioning vessels. Resting vessels were not responsible for the poor vascular delineation. Either a direct capillary blockage or an indirect blockage due to intravascular mixing of contrast media and blood occurred.
Animals↗
The bone-anchored auricular episthesis.
Total ablation of the pinna gives an unsatisfactory cosmetic result which has to be corrected. Plastic surgery procedures are generally not very successful and some sort of episthesis is preferred by many. The attachment of an episthesis is, however, often a problem. This paper is a case report of a new type of episthesis fixation arrangement. In a first session four titanium screws were implanted into the temporal bone above and behind the external meatus with a technique ensuring minimal tissue violation. Three months later when these screws were firmly integrated in the living bone, skin-penetrating titanium abutments were connected and a gold bridge was adapted to the abutments. A silicon rubber episthesis was attached to the bridge with a snap fastener. Behind this new method of episthesis attachment are several years of clinical experience of titanium implants directly anchored into various living bones and allowed to permanently penetrate skin or mucous membrane.
Carcinoma, Squamous Cell↗