Biomedical subjects
Publications and source records attributed to J I Cawood.
This paper describes the application of endosseous titanium implants that have been inserted into the vascularized bone of the radial forearm composite flap, used for mandibular reconstruction. The technique described allows full orofacial rehabilitation to be achieved, following ablative surgery and adjuvant radiotherapy.
The application of endosseous implants has extended the range of options and effectiveness of reconstructive preprosthetic surgery. Placement of endosseous implants in the edentulous maxilla is often restricted due to lack of available bone. Exposure of the underlying anterior maxillary bone frequently reveals a ridge form which is adequate in height but too narrow to accommodate endosseous implants. A horseshoe type osteotomy extending from the ridge crest into the floor of nose has been developed which allows advancement of the outer cortex to restore lost facial form and placement of an interpositional bone graft and endosseous implants to restore lost function.
When considering preprosthetic surgery of the edentulous jaws, it is important that the clinician fully understands the anatomical consequences of reduction of the residual ridges. Based on a classification of the edentulous jaws, changes in the relationship of the jaws to each other, in muscle relations and function, in the oral mucosa and in facial morphology have been measured relative to the stage of resorption of the edentulous jaws.
Glycosaminoglycans (GAG) in gingival crevicular fluid (GCF) samples were determined by cellulose acetate electrophoresis and densitometric scanning. Two GAG bands, hyaluronic acid and chondroitin-4-sulphate (C4S), were detected in GCF from implants, similar to the profile from teeth. High GCF volumes and GAG contents, notably C4S, may reflect postoperative alveolar bone responses, particularly resorption, at different stages of healing and function of successful implants. They may also indicate adverse tissue changes in failing implants. A comparison of crowned implants and matched teeth suggests that the periodontal ligament contributes to the GCF GAG profile. This may be a useful laboratory method of monitoring implants to detect adverse tissue responses at an early stage.
A study to measure the pulmonary effects of intermaxillary fixation (IMF) demonstrated that this technique produces a significant degree of airway obstruction. This may be dangerous to patients with limited respiratory reserve due to chronic obstructive airways disease. The impairment of pulmonary function can be assessed pre-operatively and should be estimated in high risk patients. Alternative management of stabilization of jaw fractures that avoid IMF should be considered in such patients.
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By comparing 27 patients who had both scintigraphy and sialography in the assessment of salivary gland disease, scintigraphy has been shown to correlate well with abnormal sialograms. It is suggested that scintigraphy could become the initial screening procedure in the assessment of salivary gland disease. A normal scintiscan is unlikely to miss significant pathology (as demonstrated by sialography), but sialography must always be performed if there is a suspicion of duct obstruction on scintigraphy. Patients suspected of focal salivary gland pathology such as tumour have not been investigated. The series documents the findings in patients who presented with facial pain, swelling or xerostomia suggesting sialadenitis, duct occlusion or Sjögren's syndrome.
The previous paper emphasised the importance of case selection in determining success in the use of the Tübingen implant system. Adherence to strict clinical techniques has an equally important influence on implant success and failure. This paper describes the surgical and restorative techniques involved in the use of the Tübingen implant and comments on the authors' initial experiences with this system.
A classification of the edentulous jaws has been developed based on a randomised cross-sectional study from a sample of 300 dried skulls. It was noted that whilst the shape of the basalar process of the mandible and maxilla remains relatively stable, changes in shape of the alveolar process is highly significant in both the vertical and horizontal axes. In general, the changes of shape of the alveolar process follows a predictable pattern. Such a classification serves to simplify description of the residual ridge and thereby assist communication between clinicians; aid selection of the appropriate surgical prosthodontic technique; offer an objective baseline from which to evaluate and compare different treatment methods; and help in deciding on interceptive techniques to preserve the alveolar process. An awareness of the pattern of resorption that takes place in various parts of the edentulous jaws, enables clinicians to anticipate and avert future problems.
Small plate osteosynthesis has been evaluated by comparing 50 successive cases of mandibular fracture treated by this technique alone with 50 successive cases of mandibular fracture treated by intermaxillary fixation. The plates show considerable advantages over other forms of fixation in that they are small, malleable and easy to insert. Furthermore, they achieve a high degree of stability. The rate of recovery of normal jaw function and normal body weight is significantly greater than with intermaxillary fixation.
To assess the accuracy with which quantitative scintigraphy reflects the true extent of parenchymal losses in diseased salivary glands, the parotid glands of vervet monkeys were unilaterally subjected to experimental injury and studied by scintigraphy and histomorphometry. The glandular 99Tcm pertechnetate uptake, relative to a standard dose, was expressed as the ratio of operated to unoperated sides. This was compared with the equivalent ratios of the weights of various salivary component tissues, morphometrically determined at necropsy. Our results suggest that uptake levels of 99Tcm pertechnetate are influenced predominantly by the mass of acinar rather than ductal tissue present. Furthermore, in comparisons between scans, because of the inherent variability in the results, quantitative scintigraphy is sensitive only to differences exceeding 25% of the gland mass.