Jan Rosenquist

Morphological Changes in Bone Following Intramedullary Implantation of Methyl Methacrylate: Effects of Medullary Occlusion: A Morphometrical Study

Using a computerized, semi-automatic morphometrical system, the morphological effects on diaphyseal rat femur following intramedullary implantation of methyl methacrylate were studied. Furthermore a comparison with the effects of periosteal elevation and removal of the bone marrow by suction was made. The changes in bone morphology were studied with the aid of microangiography, microradiography, fluorescence microscopy and histology. The results showed that there were evident differences between the postoperative course of the three procedures regarding vascular changes in the femoral cortex, bone remodelling and extent and duration of cortical necrosis. Implantation of methyl methacrylate caused greater vascular disturbance than elevation of the periosteum and removal of the bone marrow.

Bradykinin stimulates prostaglandin E2 formation in isolated human osteoblast-like cells

The effect of bradykinin on prostaglandin E2 formation in cells from human trabecular bone has been studied. The cells responded to parathyroid hormone with enhanced cyclic AMP formation and were growing as cuboidal-shaped, osteoblast-like cells. In these isolated human osteoblast-like cells, bradykinin (1 μmol/l) caused a rapid (5 min) stimulation of prostaglandin E2 formation. This finding indicates that human osteoblasts are equipped with receptors for bradykinin linked to an increase in prostaglandin formation.

Bone healing after implantation of hydroxyapatite granules and blocks (Interpore 200) combined with autolyzed antigen-extracted allogeneic bone and fibrin glue

Bone healing around hydroxyapatite granules and blocks (Interpore 200), implanted in mandibular and tibial bone cavities with or without autolyzed, antigen-extracted, allogeneic (AAA) bone, was studied in young adult rabbits. The study was done in two series. In series I, standardized bone cavities were filled with implants in granular form mixed with a fibrin glue, Tisseel, for half of the cavities. The animals were followed for 5 and 8 weeks. In all cavities implanted with AAA bone, regardless of the combination with hydroxyapatite or the fibrin glue, bone had formed in excess of the cavities, resembling exostosis formation. AAA bone significantly increased (P < 0.005 or 0.01) bone formation. In series II, a 6 x 3-mm cavity was created in the medial aspect of the proximal part of each tibia. This was filled with a hydroxyapatite block--its cross section measuring 6 x 3 mm--such that 2 mm of the block extended outside the bone surface. In alternation between left and right sides, half of the blocks were covered with a paste of AAA bone and Tisseel, and half with Tisseel with the fibrin glue alone. The observation time was 8 weeks. The area of newly formed bone within and around the hydroxyapatite blocks was significantly increased (P < 0.001) when AAA bone was used. Thus, hydroxyapatite, both as granules and blocks for supporting structures, can be successfully combined with AAA bone, the bone-inductive capacity of AAA bone being utilized.

Intraoral or extraoral approach in oblique sliding osteotomy of the mandibular ramus: A cephalometric study

Positional changes of the mandible after oblique sliding osteotomy of the mandibular rami were investigated by means of cephalometric analysis. The patient material comprised 40 patients. Twenty patients were operated upon using an extraoral approach and 20 were operated on using an intraoral approach. The patients were followed up with lateral cephalograms for 18 months after operation. In both groups, a posterior rotation of the mandible took place during the fixation period. This rotation gave a further retro-displacement of gnathion and a shortening of posterior facial height. The incidence of patients with considerable posterior rotation of the mandible was higher in the intraoral than in the extraoral group. The difference between the means of the changes in the mandibular plane angle (dEO = 4.9 degrees, dIO = 6.3 degrees) of the groups was, however, not statistically significant. Nor was there any significant difference in relapse between the two groups after release of the fixation.

Extraoral or intraoral approach in the oblique sliding osteotomy of the mandibular rami? Clinical experience and results.

The clinical results of oblique sliding (subcondylar) osteotomy of the mandibular rami performed by the extraoral or intraoral approach were compared. The patient material comprised 40 patients with mandibular prognathism. Twenty patients were operated upon using the extraoral approach and 20 patients were operated on using the intraoral approach. All patients had intermaxillary fixation for 7 weeks. The patients in both groups were followed up for 18 months. The experience of the operations was that the intraoral approach gave a shorter operation time than the extraoral approach. The extraoral approach, however, gave better visibility in the operation field and greater possibilities of manipulating the proximal fragment into an optimal position. In the follow-up evaluation, there were no significant differences between the two surgical techniques with regard to dental relapse, post-operative occlusion and mandibular function.

A comparison of paracetamol and diflunisal for pain control following 3rd molar surgery

A double-blind randomised cross-over study to compare 2 regimes of paracetamol and diflunisal for postoperative pain relief following 3rd molar surgery was designed. 35 patients received one of the regimes at one visit and the alternative at the other visit. Both drugs, namely a single dose of 500 mg of diflunisal given preoperatively or 2 doses of 1000 mg of paracetamol, given preoperatively and 4 h postoperatively, produced adequate pain relief, without the need for supplementary analgesics during the 10-h test period. The differences in the mean overall pain scores in the 2 regimes were not statistically significant.

Morphological changes in bone following intramedullary implantation of methyl methacrylate: A morphometrical study of calcium deficiency

Adult male Sprague-Dawley rats had a methyl methacrylate implant in their right femur. After 16 weeks a group of rats was given a calcium-deficient diet. The rats were followed for another 31 weeks. Due to calcium deficiency a loss of femoral bone mass occurred which was relatively greater in the non-operated femur, as compensatory periosteal bone apposition and remaining necrotic bone areas contributed to the bone mass in the operated femur. The calcium deficiency did not affect the interface between bone and implant, where a thin sleeve of new bone was formed. While the non-operated femur lost its bone through endosteal resorption, the loss of bone in the operated femur was due to intracortical resorption.

Preprosthetic surgery in the front region of the mandible

Abstract Two patient series with 17 (Group A) and 19 (Group B) patients, respectively, were subjected to sulcus extension surgery in the front region of the mandible and operated on with two different methods. They were followed clinically and radiographically for 12 months. The postoperative result in Group A (preparation method) remained unchanged during the observation period. In Group B (flap method) there was a reduction of the vertical displacement of the sulcus during the first month. Thereafter no further change was observed. With regard to the net gain in denture wearing surface, there was no difference between the methods. However, the postoperative course was less complicated in Group A. Thus the preparation method is the one to be preferred.

Intracartilaginous defects in adult sheep

Standardized, intracartilaginous articular cartilage defects were studied in the knee joints of adult sheep at 3, 4 and 6 months. The histologic and autoradiographic examinations of the articular cartilage in the margins of the defects showed superficial fibrillation and retention or increase of sulphate uptake over chondrocytes close to areas without labelled cells. These changes were mainly confined to the defect area. No progress with time could be ascertained. Desintegrated and dead chondrocytes as well as matrix alterations were ultrastructurally found in the margins of the defects. Beneath the defects in the deeper parts of the remaining non-calcified cartilage, there were matrix alterations that were not apparent with the light microscope. Microradiographic and fluorescence microscopic (after Tetracycline) examination showed loss of mineral from calcified cartilage and bone in the immediate vicinity of the defect and increased fluorescence in mineralized structures at 3 and 4 months. Moreover, at 6 months subchondral osteophytes were seen within and outside the defect area. Thus, in this experimental system superficial articular cartilage defects evoke matrix alterations in the deeper regions of the remaining cartilage and reactive changes in the mineralized structures. Bei erwachsenen Schafen wurden unter standardisierten Bedingungen intracartilaginäre Defekte des Kniegelenkes über einen Beobachtungszeitraum von 3–6 Monaten untersucht. Die histologischen und autoradiographischen Befunde ergaben, daß der Gelenkknorpel im Randgebiet des Defektes eine oberflächliche Fibrillation aufwies, wo die Chondrocyten eine teilweise erhöhte Aufnahme von markiertem Schwefel zeigten. Ein Fortschreiten dieser Veränderungen über das Defektgebiet hinaus konnte im Versuchsablauf nicht beobachtet werden. Elektroonenmikroskopisch fanden sich im Defektrand Nekrosen von Chondrocyten und eine Fibrillation der Matrix. Die Matrixveränderungen im tiefergelegenen, nicht verkalkten Gelenkknorpel unter dem Defekt waren ausgedehnter, als es die lichtmikroskopischen Befunde aufwiesen. Die Mikroradiographie und die Fluorescenzmikroskopie nach vorangegangener Tetracyclingabe ergab einen Mineralisationsverlust im verkalkten Gelenkknorpel und Knochengewebe unmittelbar neben dem Defekt und eine erhöhte Fluorescenz in den Mineralisationszonen nach 3 und 4 Monaten. Nach 6 Monaten wurden subchondrale Osteophyten innerhalb und außerhalb des Defektgebietes gefunden. Aus den Untersuchungen ergibt sich, daß ein oberflächlicher Gelenkknorpeldefekt zu Veränderungen der Matrix in den tieferen Knorpelarealen führt und reaktive Veränderungen in den Mineralisationszonen eingeleitet werden.

Anterior skeletal fixation as an adjunct to oblique sliding osteotomy of the mandibular ramus: A cephalometric study

Positional changes of the mandible and upper and lower incisors were studied by means of cephalometric analysis after oblique sliding osteotomy for the correction of mandibular prognathism. In addition to intermaxillary fixation, skeletal fixation between the anterior nasal spine and the chin was used. The patients were followed up for 18 months after surgery. During the fixation period no increase in anterior facial height was observed and at 18 months this had decreased by 2.2 mm. Nevertheless, there was an increase in the mandibular plane angle by 3.8 degrees which mainly occurred during the fixation period. The posterior facial height decreased by 4.0 mm. As to the changes of the incisors these varied between individuals, but the mean values were small. Anterior skeletal fixation prevented increase in anterior facial height and seemed to limit the posterior shortening of the mandible and the extrusion of the mandibular incisors. However, the benefits remained rather limited.