Gisle Bang

Metal particles and tissue changes adjacent to miniplates A retrieval study

Peri-implant soft tissue and bone from 12 patients undergoing removal of stainless steel miniplates and screws after healing of jaw fractures were studied with regard to histomorphology and metal content. Three patients with titanium plates were also included. Light microscopy and scanning electron microscopy with energy-dispersive X-ray microanalysis were used. Non-osseous tissue adjacent to devices of both materials showed fibrosis, including areas of mild chronic inflammation. The cellular picture was dominated by fibroblasts with small aggregates of lymphocytes and scattered macrophages. A connective tissue collar was found between the bone tissue and the screws of both stainless steel and titanium. Bone formation was also evident adjacent to screws of both materials. Stainless steel or titanium particles 5-50 microns in diameter were found in both soft tissue and bone next to implants of their corresponding bulk material. The amount of metal impregnation varied between individual sections, and fewer particles were found in the bone specimens than in soft tissue. The mild inflammatory changes were not restricted to areas of metal impregnation.

The “Scandinavian Star” ferry disaster 1990 -a challenge to forensic odontology

SummaryWith 158 victims, the fire on board the “Scandinavian Star” was one of the worlds worst ferry disasters. A team of identification experts, including dentists, were employed to secure evidence for identification and to remove the victims from the ferry. Four parallel teams, each with 2 dentists, examined and autopsied the victims at the Institute of Forensic Medicine, University of Oslo. Using the INTERPOL Disaster Victim Identification forms and aided by computers, all victims were identified within 17 days. Dental identity could be established in 107 cases (68%).ZusammenfassungMit 158 Opfern war das Feuer an Bord der “Scandinavian Star” eines der schlimmsten Fährenunglücke in der Welt. Ein Team von Identifizierungsexperten inklusive zweier Zahnärzte arbeitete auf dem Schiff, um die Leichen zu bergen. Vier Teams, jedes mit zwei Zahnärzten besetzt, untersuchten und obduzierten die Leichen am Rechtsmedizinischen Institut, Universität Oslo. Mit Hilfe des Interpol-MassenunglücksSchemas und unterstützt von Computern hat die Norwegische Identifizierungskommission die Identität von allen Opfern innerhalb von 17 Tagen festgestellt. Die zahnärztliche Identität konnte in 107 Fällen festgestellt werden (68%).

Biocompatibility and effect on osteogenesis of poly(ortho ester) compared to poly(DL-lactic acid)

Implantation of demineralized bone induces new bone formation by the action of contained growth factors, of which bone morphogenetic proteins are of prime importance. A biodegradable polymer may be used as a carrier for demineralized bone particles or recombinant bone growth factors to prevent displacement of the implant, preserve its volume and shape, and assure sustained release of the incorporated active components. A polymer for this use should be biocompatible and completely absorbed without interfering with the osteogenesis. We investigated the host-tissue response and effect on demineralized bone-induced bone formation by two biodegradable polymers, a poly(ortho ester) and an amorphous low-molecular poly(DL-lactic acid). Both polymers had a plastic consistency, could easily be molded, and adhered well to the demineralized bone particles. Demineralized bone particles were implanted alone and in combination with each of the polymers in the abdominal muscles of 45 male Wistar rats. Four weeks after the operation the implants were recovered and subjected to (85)Sr uptake analysis to quantify bone formation and histologic examination. The poly(ortho ester) provoked little inflammation; it was largely absorbed by 4 weeks, and no qualitative or quantitative effect on bone formation was found. The poly(DL-lactic acid) provoked a chronic inflammation with multinuclear giant cells, macrophages with engulfed material, and proliferating fibroblasts; part of the material was still present, and the bone formation was inhibited.

Effect of Instability on Experimental Fracture Healing

Bilateral tibial osteotomy with fracturing of the fibula was performed on ten Wistar rats weighing 300--350 g. Intramedullary nailing was performed with 1.4 mm nails after reaming. On the left side solid stainless rods were used, while on the right side the nails had a middle part made of titanium-nickel wire covered with polyvinylchloride (PVC), giving the nail a high degree of flexibility. After 8 weeks, nine of the ten flexible nails showed fracture of the central wire. The continuity was, however, maintained by the PVC tube. The bones with flexible nailing always showed hypertrophic callus while there was only scanty callus on the side with rigid nailing. Strength, deformation at fracture and stiffness were measured in a three-point bending test after removal of the solid nails and the fibulae. The strength of the tibiae was greatest on the side with flexible nailing, as was the deformation at fracture. The mean stiffness was higher in the bones with rigid nails, but the difference here was not statistically discernible.

Histologically verified bone wax (beeswax) granuloma after median sternotomy in 17 of 18 autopsy cases

Aim: To evaluate the sternum from ordinary or forensic autopsy cases with a midline sternal cutaneous scar macro‐ and microscopically and using computed tomography (CT) to detect if the haemostatic bone sealant bone wax (beeswax) had been applied after median sternotomy and if the bone wax had elicited inflammation. Methods: During a 3‐year period, the sterna of 18 consecutive cadavers (15 ordinary autopsies, 3 forensic) who prior to death had undergone surgery with median sternotomy were examined macro‐ and microscopically and with CT. In addition, one virgin sternum was smeared with bone wax at the upper half after bench sternotomy, sutured and examined with CT. Unused bone wax was examined with CT for attenuation measurements. Results: Macroscopically, bone wax was seen in 17 of 18 sterna. Acute inflammation was found in one, chronic inflammation and foreign body multinucleated giant cells were seen around the bone wax in 17 sterna. No inflammation was found in one. CT could only detect foci in the operated sterna with attenuation values from −45 to +20 Hounsfield units (HU) and values about −80 HU were found in the virgin sternum. Unused bone wax measured about −100 HU. Conclusions: Bone wax is non‐resorbable and induces chronic inflammation in the operated sternum up to 10 years after application. Measurement of Hounsfield units with CT of the operated sterna could not verify bone wax granuloma.

Filling of a Bone Defect During Experimental Osteotaxis Distraction

Gradual distraction of a tibiofibular bone osteotomy in 14 rabbits was compared with a neutral osteotomy in 14 control rabbits using an osteotaxis device as fixation. The osteotomy was distracted for a period of 8 weeks at a rate of 1 mm/week. The control osteotomies united in 5 to 6 weeks with minimal external callus formation. In the distraction group, the periosteum and endosteum participated in the filling of the distraction gap. The most vigorous osteoblastic activity was observed in the middle of the osteotomy gap (growth zone) where calcification was delayed. In the distraction group the bone united in 6 to 7 weeks, not significantly later than in the controls. Two instances of non-union (2/14) were observed in the distraction group.

Revascularization of calvarial, mandibular, tibial, and iliac bone grafts in rats.

Some studies have suggested that membranous bone grafts undergo less resorption than endochondral grafts, and faster revascularization of the former has been proposed as the explanation. We studied fresh syngeneic full-thickness bone grafts from calvaria, mandibula, tibia diaphysis, and iliac bone implanted in the back muscles of young Lewis rats. As a measure of the quantity of cancellous bone in grafts before implantation, the ratio of the total area of soft-tissue spaces to the total area of the graft was measured histomorphometrically. Revascularization in grafts 3 weeks postoperatively was evaluated by deposit of 141Ce-labeled microspheres. Both the quantity of cancellous bone (before implantation) and the revascularization (3 weeks postoperatively) were greater in the mandibular and iliac bone grafts than in the calvarial and tibia diaphyseal grafts. The results suggest that the anatomical area of harvest of bone graft is important regarding early revascurarization, but the results do not support the theory that different embryological mode of development is the cause since mandibula (high 341Ce index) and calvaria (low 141Ce index) are of membranous origin and iliac bone (high 141Ce Index) and tibia (low 141Ce index) are of endochondral origin. The difference in revascularization between the different grafts may be explained by differences in quantity of cancellous bone since cancellous bone is revascularized faster than cortical bone.

Combined preoperative treatment with cobalt and bleomycin in patients with head and neck carcinoma—A controlled clinical study

Abstract A randomised and controlled clinical study comparing cobalt plus bleomycin (3000 rad/180 mg bleomycin) with cobalt plus placebo has been carried out in 29 patients with moderately to highly differentiated squamous cell carcinomas of the head and neck. The treatment was given prior to radical surgery and all specimens examined histologically after serial section. No differences iin side-effects, operative difficulties or delayed healing were encountered between the groups. Tumour response based on clinical and histological criteria was clearly in favour of preoperative treatment with cobalt plus bleomycin compared to cobalt plus placebo. However, by histological examination in serial sections of the operative specimen residual tumour was present in a rather high proportion in both groups. The histological findings also throw doubt on the specificity of the previously reported histological changes following bleomycin treatment. The necessity of radical surgery in addition to preoperative treatment with cobalt plus bleomycin is stressed.

Bone induction by composites of bioresorbable carriers and demineralized bone in rats: A comparative study of fibrin-collagen paste, fibrin sealant, and polyorthoester with gentamicin

Host tissue response and heterotopic osteoinduction by composites of demineralized bone matrix and three different substances used as bioresorbable carriers implanted in the abdominal muscles were evaluated by strontium 85 uptake and histology 4 weeks postoperatively in 60 male Wistar rats. Both fibrin-collagen paste and fibrin sealant inhibited bone induction and produced a chronic inflammation; part of the fibrin-collagen paste was still present at 4 weeks. Polyorthoester with gentamicin was almost completely absorbed, induced minimal tissue reaction, and did not inhibit osteoinduction.

Ameloblastic carcinoma of the maxilla: A case report

A case of an ameloblastic carcinoma in an unusual situation in the maxilla is presented. The lesion is characterized histologically by areas with features of a typical ameloblastoma and areas with anaplastic transformation. A Caldwell-Luc operation was followed by a recurrence after 3 years. Due to the advanced age and poor general health of the patient an enlarged, but not radical operation was performed. There is no evidence of metastatic tumour.