Biomedical subjects
D N Thorburn
Publications and source records attributed to D N Thorburn.
Aetiology and management of the anterior dislocated disc. The anterior dislocated disc: some considerations of aetiology and clinical diagnosis.
The displacing temporomandibular joint disc presents an enigma. Modern imaging techniques of arthrography, CT, and MRI, as well as arthroscopy show that a displaced or even totally dislocated disc is not necessarily associated with disease, and such a joint can function quite without symptoms. Conversely these techniques, and notably arthroscopy, show that in some cases trauma initiates a cascade of events affecting not only the disc but also synovium, capsule, ligaments, and cartilage. Changes in synovial fluid, alterations in collagen, and associated release of pain-producing substances, cause alteration in joint dynamics. Reversible at early stages, these processes can produce adhesions which alter joint movement, including disc displacement. There is no single cause of disc displacement, but rather the effect of trauma on the interplay between structural, behavioural, and orthopaedic factors. Clinical diagnosis, excluding imaging, is briefly discussed emphasizing the concept of the barrier, and the use of diagnostic manipulation.
Familial ogee roots, tooth mobility, oligodontia, and microdontia.
The term ogee is proposed to describe dome or onion-shaped incisor roots as presented in a family study. A case of ogee permanent upper incisor teeth associated with microdontia, oligodontia, and tooth mobility is described. Forty-seven members of the proband's family were examined. The dental abnormalities were found to be of an autosomal dominant pattern of inheritance.
Exposure factors and screen-film combinations in temporomandibular joint radiography.
Exposure factors and screen-film combinations providing optimal quality are identified for transcranial and transpharyngeal temporomandibular joint views, using conventional intra-oral radiographic equipment without grids. Standardized transcranial and transpharyngeal views, using a fixed whole cadaver head, were performed. Ten readily available screen-film combinations, ranging in nominal speed 20-600, were exposed over 40-100 kV. Films were blindly and independently order ranked by three observers on the basis of sharpness and contrast of cortical outline, trabecular detail, and visualization of adjacent bony structures. Preferred screen-film combinations as a function of kV, preferred kV levels for each screen-film combination, and overall ranking irrespective of kV or screen-film combination, were established. Accepting the use of the lowest radiation dose possible for diagnostically useful radiographs but imposing arbitrarily an upper limit of 20 mGy, it was found that exposures between 50 kV and 70 kV gave the optimal result for both techniques. The amount of scattered radiation in the emergent beam differs greatly between the two techniques. The most favoured combinations for the transpharyngeal technique used screens of fine resolution. Min-r/ortho M screen and film with nominal speed 40 at 60 kV gave 8.0 mGy skin dosage at 0.8 seconds exposure; the same combination at 50 kV was the most favoured, but with skin dosage calculated at 16.7 mGy for 3.0 seconds exposure. For the transcranial technique, medium speed screens providing better differentiation of scattered radiation beams and increased speeds were preferred. Most favoured for image quality was the Lanex Fine/T-Mat G combination at 60 kV giving 17.5 mGy skin radiation dose at 1.75 seconds exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
Hemifacial microsomia label questioned.
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Mandibular dysfunction in children with otalgia.
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Temporomandibular joint dysfunction in children presenting as otalgia.
Thirty-one children between the ages of 6 and 16 years with otalgia but normal eardrums were investigated for temporomandibular joint dysfunction. Ear disease was excluded by microscopic examination, pure tone audiometry and impedance tympanometry. Dental disease was excluded by clinical and radiographic examination. Temporomandibular joint dysfunction was diagnosed by finding tenderness of the joint or masticatory muscles in at least two separate sites at one examination. Twenty-one patients were assessed as having joint dysfunction and in 18 of these the diagnosis was made when the child was seen in pain. Tympanometry on painful ears did not reveal any abnormality or trend in the values for compliance or middle ear pressure. Simple methods of treatment were effective in all cases. Temporomandibular joint dysfunction should be suspected in any child who complains of recurrent otalgia in the absence of dental and otological disease.
Giant cell hyalin angiopathy or pulse granuloma.
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