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Biomedical subjects

J Wittbjer

Publications and source records attributed to J Wittbjer.

11 recordsLinked to original sources
PubMed2001

Displacement of the mandible in a child with congenital unilateral temporomandibular joint ankylosis treated with two-stage condylar replacement: a long-term study with the aid of roentgen stereometric analysis.

OBJECTIVE: To monitor mandibular displacement in three dimensions with a high degree of accuracy before, during, and after treatment. DESIGN: Prospective roentgen stereometric analysis from age 3 years 7 months to age 13 years 8 months. SETTING: Center for Craniofacial Anomalies and Department of Maxillofacial Surgery, Malmö University Hospital, Malmö, Sweden. PATIENT: Girl with unilateral congenital temporomandibular joint (TMJ) ankylosis and marked facial asymmetry. INTERVENTIONS: Epipharyngeal inspection at age 2 years 6 months and insertion of implants under general anesthesia. Resection of the affected right condyle at age 5 years 4 months, replacement of the ramus-condyle complex with a custom made titanium prosthesis at age 5 years 5 months, and replacement of the artificial condyle by a costochondral graft at age 9 years 7 months. Roentgen examinations were performed at intervals from age 3 years 7 months to age 13 years 8 months. Body length was measured annually. MAIN OUTCOME MEASURES: Stereo roentgenograms were digitized by the Department of Orthopedic Surgery, Malmö University Hospital. RESULTS: Unexpected lowering of the mandible occurred before treatment. Each procedure had a distinct effect on the direction of mandibular displacement. There was little or no pathological involvement of the functional matrix. Growth of the costochondral graft exceeded growth of the unaffected TMJ. Anterior displacement as well as rotation and tilting of the mandible to the unaffected side accelerated after the age of body peak height velocity. CONCLUSIONS: Accurate monitoring of mandibular displacement may contribute to a rationale for clinicians' decision on treatment protocol and reveal compensatory differential growth.

Adolescent↗
PubMed1989

Changes of the profile after advancement genioplasty.

Surgical advancement of the chin, and postoperative relapse, were studied during a three-year period in 17 patients. Changes were measured on lateral cephalograms obtained at certain intervals. Sagittal skeletal changes were recorded parallel to the Frankfort Horizontal plane. Soft tissue changes were recorded by advancement of soft tissue Pogonion along a line parallel to the mandibular base line and by the increase of the angle NFL/NCL. The average skeletal advancement was 8 mm with a relapse of 1 mm two months after surgery. No further changes were registered during a three-year observation period. The average soft tissue advancement was 7.5 mm from two months after surgery and no relapse was found after this time. The soft to hard tissue ratio of the changes was 0.94 which corresponds to results reported in the literature. There was no correlation between the average amount of advancement and the amount of relapse. The range of changes showed a wide variation, however.

Adolescent↗
PubMed1987

Bone matrix and marrow versus cancellous bone in rabbit radial defects.

Implants of demineralized bone matrix induce new bone formation. In order to estimate the possible clinical usefulness of this phenomenon, autologous cancellous bone grafts were compared with composite grafts of bone matrix and marrow. Cancellous bone from the tuber ischii of the rabbit was transplanted to a preformed radial defect in the same animal. On the opposite side, a similar defect was filled with a mixture of either allogenous or autogenous bone-matrix particles and autogenous bone marrow. After 25 days, calcium 45 was injected intravenously. Three days later the animals were killed. Standardized segments of the rabbit's forearms, containing the middle of the defect, were cut out, ashed, and analyzed for 45Ca activity. No side difference in 45Ca deposition was found. The callus ash weight of the allogenous matrix-transplanted side was approximately 60% of that of the cancellous bone side. This side difference of ash weights corresponds to the estimated initial mineral content of the cancellous graft. Nontransplanted defects had very low ash weight and 45Ca activity. Thus, in the rabbit, composite grafts of bone matrix and marrow produce a bone yield comparable to that of cancellous bone.

Animals↗
PubMed1986

Pulverized bone matrix as an injectable bone graft in rabbit radius defects.

A segment of the rabbit radius diaphysis was excised, demineralized, and pulverized. The demineralized matrix particles were mixed with autologous bone marrow from the femoral canal and injected into the defect from which it had been excised. On the contralateral side, the demineralized bone was reimplanted without pulverization, but with bone marrow. The bone yield was measured by radiographic planimetry and Tc99m MDP scintimetry. The forearms of the rabbits were sectioned into transverse segments, including the middle of the radius defect. The ash weights and the Ca45 content of these segments were measured. After two weeks, the ash weight was greater on the pulverized than on the unpulverized side; but by four weeks, measurements showed no difference. In general, the injectable bone matrix preparation did not interfere with bone repair. In comparing the Tc99m and Ca45 methods, the latter provided high-precision data with respect to the biologic variation.

Animals↗
PubMed1985

Composite grafts of demineralized compact bone and marrow under systemic biosynthetic growth hormone treatment.

The influence of systemic treatment with biosynthetic human growth hormone on bone formation was studied, comparing rabbit radial bone defects grafted with demineralized autologous bone with contrallateral defects grafted with a composite including bone marrow. At 14 and 28 days after operation the bone-forming process was evaluated by roentgenography (planimetry included), and by scintigraphy after injection of 99mTc-labeled dicarboxypropane diphosphonate. At 28 days autoradiography was also performed. The roentgenographic and scintigraphic examinations revealed no difference between the grafted sides at either 14 or 28 days postoperatively. The elimination, after 14 days' growth hormone treatment, of a previously found difference between the marrow- and the nonmarrow-grafted sides might be an indication of accelerated osteogenesis at the beginning of the healing process.

Animals↗
PubMed1984

On direct currents and bone formation in demineralized bone transplants.

The effect of direct current on the remineralization of a bone defect was studied in the rabbit. Bone defects in the radius of both forelegs were grafted with demineralized autologous bone. On both sides platinum electrodes were placed around the graft, and one side was connected to a power source delivering 20 microA constant current during the experimental period of 28 days. The remineralization was evaluated 14 and 28 days after operation by scintigraphy and roentgenography, planimetry included. At 28 days after operation this evaluation was supplemented by autoradiography. Roentgenographically, there was no difference between the two sides. At 14 days after operation scintigraphy demonstrated a minor delay in bone formation at the electrostimulated side. Between 14 and 28 days a significant increase in activity was noticed. On both sides, autoradiograms showed areas without uptake around the wires. It was concluded that direct currents of the studied magnitude have a negative influence on the primary bone induction process but also that it seems to influence the mineralization positively later in the bone-forming process.

Animals↗
PubMed1983

Bone formation in demineralized bone transplants treated with biosynthetic human growth hormone.

The influence of local administration of biosynthetic human growth hormone on the bone formation in a rabbit bone defect grafted with demineralized autologous bone was studied and compared to contralateral saline administration. The growth hormone was produced by hybrid DNA-technique and administered locally to the bone defect with the demineralized bone implant by an osmotic pump delivering 5 microliters/h during 14 days. At 14 and 28 days after operation the bone forming process was evaluated by roentgenography, planimetry included, and scintigraphy after injection of 99Tcm-labelled DPD. At 28 days after operation also autoradiography was performed. The roentgenographic and scintigraphic examinations revealed no influence from growth hormone neither 14 nor 28 days postoperatively. Centrally in the remineralized grafts the roentgenograms 28 days after operation showed radiolucent areas which in corresponding autoradiograms showed no uptake of 99Tcm. These areas turned out to be remnants of matrix. It is suggested that growth hormone has no influence on the bone induction process during the first 14 days when administered to bone matrix, probably due to relative lack of osteogenic cells. This study contributes a base for further evaluation of factors pertinent to hormonal stimulation of bone matrix transplants.

Animals↗
PubMed1983

Osteogenetic activity in composite grafts of demineralized compact bone and marrow.

The effects of a composite graft of autologous marrow and demineralized autologous compact bone on the healing of a surgically created bone defect were observed in adult rabbits. A segment of the radius was bilaterally resected, demineralized, and replaced. On one side the bone graft was supplemented with autologous marrow. The new bone formation was measured 14 and 28 days after operation by roentgenography, including planimetry with scintigraphy and autoradiography using 99mTc-labelled MDP. The composite graft, i.e., demineralized compact bone and marrow, had a significantly higher (p less than 0.01) bone formation rate 14 days after operation compared with the graft with demineralized compact bone in the opposite radius. At 28 days, however, there were no differences between the sides. Viable autologous marrow cells and demineralized autologous compact bone graft accelerate the rate of osteogenesis, but only at the beginning of the healing process.

Animals↗
PubMed1982

Bone formation of transplanted autologous bone matrix in rabbit evaluated by technetium radionuclide bone imaging.

In adult rabbits a 12 mm piece of the radius was bilaterally resected and subsequently decalcified. One piece was placed in one of the radial defects and the other in a skin tube on the back. The other radial defect served as a control. The bone formation process was evaluated by roentgenographic examination and quantified radionuclide bone imaging by technetium diphosphonate scintigraphy at 3 and 6 months postoperatively. Reliability of the scintigraphy method was assessed by means of testing interexamination variability where the same sample was measured twice and where no significant difference was found. In the defect restituted with decalcified bone matrix there was a significantly (p less than 0.01) higher bone formation rate at 3 months postoperatively, with a mean increase of 47% compared to the control side. In the skin tube the implanted matrix showed mineral formation both at 3 and 6 months postoperatively and increased radionuclide uptake compared to the adjacent tissues. Technitium radionuclide imaging was found to be a suitable method for evaluation of the bone formation in these small defects.

Animals↗
PubMed1982

Osteogenetic properties of reimplanted decalcified and undecalcified autologous bone in the rabbit radius.

In facial reconstructive surgery extensive studies have been performed to find substitutes to autologous vital bone as grafting material. Decalcified homologous compact bone has been found to possess a capacity of inducing new bone formation in rabbits whereas the application in man has not been successful thus far. In order to investigate the osteogenetic properties in autologous devitalized bone, the difference in bone forming capacity between decalcified and undecalcified devitalized autologous bone was studied. In rabbits, from the radius of each foreleg a piece of bone was resected, rinsed from periosteum and marrow whereupon one was decalcified in 0.6 N HCl. Both pieces were reimplanted in the radial defects 3 days later. The healing process was examined by radiography, light- and fluorescence microscopy. Decalcification seems to accelerate the osteogenetic process when bone is reimplanted to a defect in the rabbit radius.

Animals↗