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Biomedical subjects

J M Symington

Publications and source records attributed to J M Symington.

18 recordsLinked to original sources
PubMed1992

Clinical prosthodontic management of a new implant system.

Just prior to the advent of the branemark implant, the Harvard consensus on implantology condemned all maxillary implants. While implant utilization has skyrocketed in the last few years integration of implants in the maxilla is a persistent problem and even the branemark implant enjoys a lower success rate in this bone. These observations underscore the higher failure rate of the maxillary implant and suggest the need for development of a new implant design configuration that would favour long term successful integration despite the attenuated maxillary attributes. Such is the intent of the ostial implant. The basic considerations concerning this device, its bioengineering, experimental performance and clinical trials are discussed elsewhere. The purpose of this paper is to describe clinical prosthodontic applications of this implant system.

Dental Implants↗
PubMed1991

Postoperative computed tomography study of pterygomaxillary separation during the Le Fort I osteotomy.

Computed tomography (CT) was used postoperatively to assess the pterygomaxillary region in 12 orthognathic surgery patients who had had a Le Fort I osteotomy. Although pterygomaxillary separation was successful in all cases, in only 41.6% of the sides did fractures of the plate not occur. The incidence of low pterygoid plate fracture was 37.5% and that of high pterygoid plate fracture was 25%; 4.2% of sides showed a maxillary tuberosity fracture. Multiple fractures were observed in 8.3% of separated plates. Of 17 pterygoid plates judged clinically to be intact, only 10 were intact as assessed by CT. The significance of these findings and application of CT to evaluation of modifications to the Le Fort I osteotomy is discussed.

Adult↗
PubMed1988

Rhabdomyosarcoma of the maxillary sinus: review of the literature and report of a case.

A case of rhabdomyosarcoma of the maxillary sinus is reported. A brief review of the origin, histomorphology, classification, clinical presentation, behavior, prognosis, and treatment is given relative to occurrence in the maxillary antrum. Misinterpretation of the microscopic findings can delay the histologic diagnosis. An error in tissue diagnosis may be minimized by awareness of a chance encounter with this lesion.

Adult↗
PubMed1988

Osseointegrated dental implants in conjunction with bone grafts.

This paper relates to the experience with 12 patients who received osseointegrated dental implants of the Branemark design associated with bone grafts. 4 patients had iliac crest grafts, 2, of which were inserted together with the implants. Two had metatarsal reconstruction of the anterior mandible with the implants installed at a later date. 2 patients had particulate marrow grafts with immediate installation of the implants. Of the remainder, 1 had a late implantation of a myo-osseous flap utilizing the clavicle and the other delayed implantation of a split rib graft. The mean age of the patients in this series is 49.5 years. The mean loading time for completed cases is 18 months. 7 patients have had their dentition successfully restored, 3 lost the initial implants, 2 of which have been re-operated. One patient died prior to loading and one awaits the final surgical procedure. The results of the particulate marrow and split rib grafts were disappointing. The remainder suggest that osseointegrated dental implants may be utilized with appropriate bone grafting techniques to restore the dentition in patients with severe bone loss or following the surgical ablation of malignant disease.

Adult↗
PubMed1988

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↗
PubMed1987

Interface between titanium 6,4 alloy implants and bone.

This paper presents the results of animal studies on the interface between 6 aluminum, 4 vanadium, titanium alloy and bone. 7 New Zealand white rabbits were anaesthetised and a new design of threaded implant inserted into the tibial metaphysis of each leg. 3 further animals had fine lathe turnings inserted in the same site. The animals were sacrificed 7 weeks later and the implants removed together with the surrounding bone. After suitable processing of the specimens, they were subjected to scanning and transmission electron microscope studies. Compact bone was found in close proximity to the surface of the metal. With higher magnifications, the bone was found to be in intimate contact with the metal. There was no suggestion of the presence of cells or uncalcified collagen fibres between the bone and the implant. At the highest magnification, there was the appearance of a homogenous transition from the bone to the metal, suggesting a biological adhesion.

Alloys↗
PubMed1985

Morphology of the developing articular disc of the human temporomandibular joint.

The morphology of the developing articular disc of the temporomandibular joint in eight human fetuses, ranging in age from 13 weeks to 17.5 weeks, was studied. The shape of the articular disc at the time of initial delineation resembled the shape of the adult articular disc, suggesting a predominantly genetic determination. Elastin fibers were not demonstrated. The vascularity of the fetal articular disc was confined to the anterior and posterior thickened peripheral zones, with no evidence of capillaries in the thinner intermediate zone. Lateral pterygoid muscle fibers inserted into the medial aspects of the developing articular disc.

Cartilage, Articular↗
PubMed1975

Streptococci isolated from post-extraction bacteraemias.

One hundred and fifty streptococci were isolated from blood cultures taken following the extraction of teeth. The cultural, biochemical and serological characteristics of the organisms are presented and their antibiotic sensitivities discussed. It is shown that a detailed assessment of these organisms can be made rather than considering them all as Streptococcus viridans.

Humans↗