Showing papers on "Osseointegration published in 1986"

The long-term efficacy of currently used dental implants: a review and proposed criteria of success.

Abstract: Criteria for the evaluation of dental implant success are proposed These criteria are applied in an assessment of the long-term efficacy of currently used dental implants including the subperiosteal implant, the vitreous carbon implant, the blade-vent implant, the single-crystal sapphire implant, the Tubingen implant, the TCP-implant, the TPS-screw, the ITI hollow-cylinder implant, the IMZ dental implant, the Core-Vent titanium alloy implant, the transosteal mandibular staple bone plate, and the Branemark osseointegrated titanium implant An attempt has been made to standardize the basis for comments on each type of implant

Osseointegration of titanium implants.

Abstract: Forty-eight screws, six double cylindrical implants and six T-plates were inserted into the tibia or femur of 6 dogs. Two titanium screws were inserted into the proximal tibia of 5 patients to anchor a titanium mould. The implants were removed en bloc with adjacent bone tissue after 3 to 14 months. They were sectioned using a technique that allowed analysis of the intact tissue-to-metal specimens. Osseointegration, defined as a direct bone-to-implant contact without interposed soft tissue, was confirmed in all screw-shaped implants while the cylindres had only partial bone contact as did the T-plates. We conclude that osseointegrated implants may be applicable in joint reconstruction for arthrosis or rheumatoid arthritis.

Threaded versus porous-surfaced designs for implant stabilization in bone-endodontic implant model.

Abstract: An endodontic implant model system was used to compare the effect of implant design on stabilization in bone. Specifically a porous-surfaced design was compared to conventional threaded and smooth-tapered endodontic implant designs. All implants were placed in immediate function thereby assessing the effect of early limited movement on the fixation achieved. A total of eighty-three endodontic implants were inserted in the mandibles of six adult mongrel dogs. Animals were sacrificed immediately after implantation and after 3, 6, and 12 months. Implants were evaluated by clinical and radiographic examination and after animal sacrifice by pull-out tests of the implant from the tissues, SEM examination of the pulled-out implants and, finally, histology. The pull-out test results indicated increasing shear strength with implantation time for the porous-surfaced implants in contrast to the gradual loss of fixation for the threaded implants and the continuous low shear strength for the smooth implants. Histological studies and SEM examination indicated the reason for these changes. Smooth implants became encapsulated by fibrous connective tissue from early post-implantation time periods. Threaded implants, although initially mechanically interlocked with bone, developed a fibrous connective tissue capsule that gradually thickened with time until, by 6 months, little mechanical interlock of bone and implant was present. It was assumed that this fibrous capsule thickening was caused by implant movement. The porous-surfaced implants, however, became stabilized by bone ingrowth and showed more extensive bone formation within the surface pores with time. It is concluded that for implants that are made functional immediately after implantation, as in this study, porous-surfaced implants can become strongly fixed by bone ingrowth, in contrast to conventional threaded or smooth-surfaced designs, thus presenting a more favourable long term prognosis.

Tissue reactions to titanium endoprostheses. Autopsy studies in four cases.

Abstract: Four cementless prosthetic hip implants of Ti-6Al-4V-alloy with and without longitudinal grooves and Al2O2 ceramic ball heads, with implant periods of 3, 4, 5, and 10 months, were sectioned and examined histologically in undecalcified thin ground sections. Especially on the medial and lateral sides of the prostheses, there was direct bone-to-metal contact without interposed connective tissue, spreading to the dorsal and ventral areas of the prosthesis shaft, which was considered osseointegration. This is based mainly on the technique of implantation with primary stability in the cortical bone by press-fit and on the bioinertness of the titanium alloy. Ungrooved prosthesis areas seem to favor bone growth at the shaft. The secondary bone ring, occurring on the dorsal and ventral areas of the prosthesis, with evidence of further bone remodeling with the passage of time, indicates that osseointegration is a dynamic process that continues to improve prosthetic stability.

Dental Implants: Tissue-Integrated Prosthesis Utilizing the Osseointegration Concept

Abstract: As an alternative to conventional removable dentures, osseointegrated dental implants can now be used in carefully selected edentulous or partially edentulous patients. The implant consists of a dental prosthesis and an anchorage unit made up of screw-connected components. The implantation procedure is performed in two phases: (1) fixture installation and (2) fixture uncovering and abutment connection. After completion of these surgical procedures, the dental prosthesis is fabricated and inserted. Follow-up examinations are scheduled at 1, 3, and 6 months and then annually thereafter. During a 2-year period at the Mayo Clinic, 358 osseointegrated dental fixtures were implanted in 70 patients. The overall success rate in this consecutive series of patients was 98%, and the associated complications were minimal and easily resolved.

A fixed prosthodontic technique for mandibular osseointegrated titanium implants

Abstract: A detailed technique has been presented for the fabrication of a fixed prosthesis supported by osseointegrated titanium implants The fixed prosthodontic technique is based on the original Swedish procedure Several new dental products have been added, and some refinements in technique have been made in an effort to consistently produce a fixed prosthesis that fits, functions, and satisfies today's esthetically conscious patient Branemark's tissue-integrated prosthesis (TIP, Bofors Nobelpharma, Inc) is the only dental implant system with two decades of high-quality longitudinal clinical experience A fixed prosthesis supported by osseointegrated implants offers a treatment modality that is predictably successful (Fig 21)

The biologic interface between bone and cementless femoral endoprostheses

Abstract: Femoral canal membrane tissue from patients who had revision of an uncemented endoprosthesis to a total hip replacement was analyzed and interlocking bone specimens were retrieved from implant fenestrations to compare membrane histology with microscopic bony remodelling. Radiographs of each hip were evaluated for bony adaptations and correlated with implant stability and interface histology. Uncemented canal membranes are composed mostly of mildly cellular dense connective tissue. Significant inflammation is rare, even in the presence of moderate metallic debris. A fibrocartilage interface often occurs above interlocking bone in areas subject to direct compressive loads. A thin membrane helps to distribute loads evenly from the rigid implant to more compliant bone. Dense lines of bone around the implant stem may be a biologic response indicating a steady-state, load-sharing equilibrium; they are not a reliable sign of implant instability. Retrieved interface membranes allow a direct view of the prosthetic-bone junction of human joint implants. In the absence of polyethylene and methacrylate wear debris, the membrane contains quiescent fibrous tissue with little inflammation. Membrane formation appears to be a mechanical adaptation to improve load distribution in the proximal femur. Presence and function of the membrane must be considered in the design and application of future press-fit implants.

Metacarpophalangeal Joint Replacement with Osseointegrated Endoprostheses

Abstract: A new type of endoprosthesis for reconstruction of the metacarpophalangeal (MCP) joint has been tested. The novel arthroplasty consists of a joint mechanism with two screw-shaped fixtures for bone anchorage. These fixtures, of commercially pure titanium, are gently screwed into the anchoring bone on each side of the diseased joint, the aim being to achieve osseointegration, i.e. a direct contact between implant and bone without interposed soft tissue layers. The hand was immobilized in a dorsal splint for 8-10 days post-operatively after which a carefully controlled mobilization program was initiated. In principle, the titanium fixtures, the surgical technique and the primary immobilization represent an approach similar to that previously used in various reconstruction procedures of the jaw. This paper describes 5 case histories of reconstructions required because of osteoarthrosis in a single MCP joint. Prior to the operation, all patients suffered from severe problems resulting from their arthrotic joints and they had not been able to work for several months. After surgery they were evaluated by a clinical assessment program and X-rays were taken at various times of follow-up. As well as visual inspection all radiograms were subjected to densitometry by means of a computer-based image-analysis system in order to provide information on the development of bone density in the bone-to implant interface region. From a functional point of view the treatment with osseointegrated prostheses must be regarded as being successful. All patients were able to go back to their original work and their hands had a satisfactory range of movement and grip strength with no signs of impaired function on longer follow-up time. Clinical problems were one re-operation, one case of implant fracture and one case requiring exchange of the joint mechanism. The computer-assisted evaluation of the radiograms revealed the presence of calcified tissue in many sections where the naked eye was not capable of differentiating any bone. In conclusion, it seems possible to establish osseointegration of MCP-endoprostheses in the arthrotic human joint in complicated cases which were regarded as contraindicated for any other joint arthroplasty.

Elongation of brachymetatarsy with ceramic implant: a roentgenographic evaluation of its utility

Abstract: The metatarsal bone was elongated by intercalary implantation of a single-crystal alumina ceramic in 7 patients with brachymetatarsy. The implants were encased with new bone 24 months after surgery and resulted in 5.2 to 9.2 mm elongation of the metatarsal bone. The response of the bone to the ceramic implant was observed roentgenographically. No resorption or pseudoarthrosis of the bones, nor loosening or breakage of the implants, were observed. The alumina ceramic implant proved to be a useful substitute for a bone graft, because of its biocompatibility and strength.

An implantable hearing device: osseointegration of a titanium-magnet temporal bone stimulator.

Abstract: The use of bone conduction hearing devices has recently entered the realm of implantable prostheses and solid-state electronics, resulting in improved fidelity and applicability for a wider range of patients. One particular device, a temporal bone stimulator (TBS), consists of an external sound processor and implanted portion to cause vibration under the skin. An implantable temporal bone stimulator screw constructed of titanium alloy with a permanent magnet can be vibrated by inductive transcutaneous coupling. The safety and osseointegration of the TBS bone screw were tested in adult goats that were free-field stimulated at 75 dB with the TBS processor for 4 to 21 weeks. Histologic comparisons of the soft tissue and bone adjacent to active and passive screws revealed no remarkable differences between them with bone growing in the interstices of the threaded portion. Evidence for mild reorganization of bone was shown with Goldner's stain, which differentiated bone that was young and unmineralized from bone that was older and mineralized. Reorganization was evident in both the active and passive sites and there was no remarkable difference between the two in a blind study. Additional evidence for the integrity of the implant was obtained by subjecting a calvarium containing both screws to a 5000 gauss magnetic field for 10 minutes of a nuclear magnetic resonance head scan. The calvarium was first dissected free from overlying skin and connective tissue. The magnet-containing screws were not loosened. We conclude that the implanted screw portion of the TBS implantable hearing device is well-integrated into the temporal bone. Mild stimulation of new bone growth indicates a healthy long-term viable implant for bone conduction amplification of sound.

Clinical application of dental root implant coated with bioglass

Abstract: The clinical application for a period of 3-years, from 1983 to 1985 involving 52 dental root implants, was carried out in the mandibular molar region and in which 1 to 3 of the teeth were lost. An implant consisted from Fe-Cr-Ni-Co alloy (similar to AMS-5376) coated with bioglass and was conical in shape with a round bottom. Implants were divided into 3 types, ranging in different lengths and diameters; small (S-type), moderate (M-type) and long (L-type). Using a diamond bur with pores for flowing water, in order to refrigerate the bone, a socket was drilled out for implantation with caution where the implant was tight.The socket wound following implantation was immediately closed using a mucoperiosteal flap. The gingival mucosa located directly above the implant was resected 3 months later. A bonding between the implant and the surrounding bone was ascertained, then a post-core and an upper structure of the root implant was constructed and cemented. The results are as folows:1) In the surrounding tissues, there were slight inflammatory reactions for 4 or 5 days after implantation and no physical obstruction due to implantation.2) The implant must be very tight and secure in the socket in order to obtain a better bonding with bone and bioglass.3) In the X-ray finding, an unclear border when bonding between bone and implant was ascertained, and a lineal radiolucency when it was not, were observed.4) In acoustoelectric diagnosis, amplitude and cyclic waves, under the condition of wellfitting or bonding between bone and implant in the socket, were small and short, and to the contrary they were large and long.5) In 17 of 23 cases (74%) of M-type implants, occlusion due to construction of the upper structure was recovered. On the other hand, the S-type and L.type implants were removed mostly because of no bonding.Furthermore, the results of implantation will be advanced through improvement with instruments and skills. Therefore, it may be possible to employ the implant procedure in dental clinical situations.