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Biomedical subjects

T Albrektsson

Publications and source records attributed to T Albrektsson.

At least 91 records · Page 5Linked to original sources

Local application of growth-factor IGF-1 to healing bone. Experiments with a titanium chamber in rabbits.

In order to study the effects of bone healing, insulin-like growth factor 1 (IGF-1) was continuously applied with a minipump to a healing bone callus located inside a titanium chamber in a rabbit tibia. After 2 weeks, 99mTc-MDP uptake and calcium content were measured. IGF-1 decreased 99mTc-MDP uptake, and thus the mineral turnover rate, but the amount of bone mineral was unchanged. Probably the normal endogenous production of IGF-1 is already optimal for healing in this model.

Animals↗

Influence of external administration of epinephrine on bone regeneration.

The effect of local administration of epinephrine was tested in a rabbit experimental model. Identical commercially pure titanium implants were inserted in the right legs of New Zealand white rabbits after pretreatment with epinephrine; the left legs served as controls. This acute administration of epinephrine was shown to have no significant impact on the incorporation of the implant as measured after 7 weeks.

Animals↗

Osseointegration: current state of the art.

In controlled multicenter studies of the Brånemark osseointegrated implant, there was a maxillary 5-year success of 86.4 per cent and a mandibulary 5-year rate of success of 96.8 per cent. A total of 80 Brånemark maxillary bridges have been followed for 5, 10, and 15 years with success rates of 96, 95, and 93 per cent. Altogether, 83 mandibular bridges demonstrated a success rate of 99 per cent over 5, 10, and 15 years of follow-up. Similar figures have been reported for partially edentulous patients with a shorter follow-up time. The ITI-implant is another well documented osseointegrated system, whereas other frequently used osseointegrated oral implants have been poorly documented. It is concluded that many currently used osseointegrated products will probably end up in results as poor as those previously reported with soft-tissue-anchored devices.

Biocompatible Materials↗

Wound healing in the bone chamber 1. Neoosteogenesis during transition from the repair to the regenerative phase in the rabbit tibial cortex.

The optical bone chamber technique that includes intravital microscopy is described and is then applied to measuring primary wound healing neoostogenesis in rabbit tibia cortical bone during the period when fibrovascular tissue is being replaced by regenerating osteovascular tissue. The small population of rabbits sampled allowed only tentative conclusions. The quantitative measurements, a direct from of histomorphometry, are applied to determine the consistency of observations, with the hypothesis that healing into the bone chamber slit-gap follows the pattern of primary bone regeneration established as "characteristic" by other studies. The results supported the hypothesis and showed that bony ingrowth started during the third postoperative week (W3) with a maximum linear growth rate of 85.5 micron/day for a bone front. Evidence for remodeling by W6 was also obtained. While the bone chamber environment for tissue ingrowth is artificial, it can generate quantitative data that may provide a statistically valid basis for modeling pathophysiologic processes associated with bone wound healing.

Animals↗

Drug test chamber: a titanium implant for administration of biochemical agents to a standardized bone callus in situ.

A titanium implant in which a conduit is gradually filled with ingrowing bone (the Bone Harvest Chamber) has been modified to allow continuous local treatment of the conduit tissue with biochemical agents. Implants were inserted bilaterally in rabbit tibiae. The tissue content of the bone ingrowth conduits was studied with histology, 99mTc-MDP scintimetry and measurements of total calcium content. Bone was formed in the conduit by endochondral formation starting at both ends and continuing until fusion in the middle. After 2 weeks the bone had not yet met in the middle where fibrous tissue was seen. In eight animals 3H-proline was applied via one of the chambers, with the contralateral chamber as a saline-treated control. The collagen of the harvested tissue from the 3H-proline treated side had a 3H-hydroxyproline content 1000 times greater than had the control side. The 'drug test chamber' makes possible the study of local effects of drugs on healing of mature bone in vivo.

Animals↗

Comparison of bone reactions to coated tricalcium phosphate and pure titanium dental implants in the canine iliac crest.

Titanium and TCP-coated implants were compared after insertion in the canine iliac crest. Observation time was 14 wk. Evaluation included pull-out tests, energy dispersive X-ray analysis, and histologic examination of in situ, undemineralized implants. The TCP-coated implants were more firmly attached to bone than were the titanium implants. The calcium/phosphorus ratios around the titanium implants were higher than around the TCP-coated implants. Both types of implants were closely surrounded by bone after a 14-wk implantation.

Animals↗

Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants.

Fourteen Swedish teams outside the University of Gothenburg, each with minimally three years' experience in the Nobelpharma osseointegrated implant participated in a retrospective multiclinic study. The total number of consecutively inserted implants at the 14 clinics was 8139. The outcome of every implant was reported and all implant failures, irrespective of when they occurred, were published. The success criteria included absence of implant mobility, absence of radiolucent zones on x-rays, and an annual bone loss after the first year of less than 0.2 mm. In the mandible 334 implants were followed for five to eight years, with only three failures, for a success rate of 99.1%. In the maxilla 106 implants were followed for five to seven years, with a success rate of 84.9%. In irradiated and grafted mandibles, 56 implants were inserted and none was lost during a follow-up of up to five years. In the irradiated maxilla there were 16 implants inserted with three reported failures and in the grafted upper jaw 71 implants were inserted with 12 failures. The proportions of mandibular and maxillary sleeping implants were 0.8 and 0.3%, of patient drop-out implants 0.3 and 0.6%, and of patient death implants 0.9 and 1.2%, respectively. It was concluded that the osseointegrated implant, if inserted according to the guidelines of Brånemark, results in a very high degree of clinical success, thereby meeting any published oral implant success criteria.

Clinical Trials as Topic↗

Influence of direct currents on bone vascular supply.

Electrical stimulation with a DC of 5 microA was found to result in macromolecular leakages in the microcirculation of rabbit metaphyseal bone. The blood flow rate of living bone did not change during 2.5 hours of electrical stimulation. Over a follow-up time of up to 11 weeks it was observed that vessels close to bone borders increased in size and that the number of bone capillaries increased, simultaneous with an increase in bone formation.

Animals↗

Bone formation rate in osseointegrated titanium implants. Influence of locally applied haemostasis, peripheral blood, autologous bone marrow and fibrin adhesive system (FAS).

The influence of local application of haemostasis, peripheral blood, autologous bone marrow and Fibrin Adhesive System (FAS) on bone formation rate in osseointegrated titanium implants, were studied. The Bone Harvest Chamber (BHC) implant utilized has a penetrating canal, enabling osseous ingrowth in situ. After integration of one implant into the cortex of the proximal tibial metaphysis of a rabbit, newly formed bone was harvested in repetitive three-week periods. The specimens were quantified by microradiography-videodensitometry and subjected to further histological examination. The amounts of bone formed in two equally treated chambers in the same animal were compared. It was concluded, that the conditions for bone regeneration in an osseointegrated titanium implant are excellent, minimally influenced by locally applied haemostasis, peripheral blood and autologous bone marrow. FAS pretreatment on the other hand was found to impair bone formation.

Animals↗

Implant fixation improved by close fit. Cylindrical implant-bone interface studied in rabbits.

Cylindric titanium implants of three different diameters were inserted and stabilized in a 3.7-mm burr hole in the rabbit tibia. The purpose of the study was to investigate the interfacial reaction to screw- and cylinder-shaped implants, and to determine if there is a critical gap at the insertion between bone and implant that prevents direct cortical bone apposition on the implant. The study indicated that this critical gap approached zero.

Animals↗

A bone chamber for investigation of gas pressure. Oxygen tension measured in rabbits.

Titanium implants containing a chamber that allowed ingrowth of bone were modified from a previous design to allow the use of oxygen microelectrodes. The modification consisted of the placement of ports in the superior surface of the implant for the insertion of oxygen electrodes into the tissue within the bone growth chamber. Forty titanium bone growth chambers were inserted into the proximal tibial metaphyses of 20 rabbits. From 2 to 20 days, oxygen tension was measured inside the chambers of 2 rabbits immediately prior to death. The oxygen tensions increased, declined, and increased again. Our results indicate that oxygen tensions fluctuate during the initial period of healing reflecting cellular changes in the callus.

Animals↗