Biomedical subjects
Publications and source records attributed to J W Ferguson.
A technique is described for bonding gold traction chain directly to the enamel surface of unerupted teeth using a visible light-cured adhesive. This method obviates the need for a bracket and relies on direct, rather than transmitted illumination.
It has been suggested that the consultant orthodontic service and specialist practitioner service should have different roles, with the former concentrating its treatment input on the management of severe malocclusions. In an attempt to determine whether referring dental practitioners appeared to be aware of these differences, 100 consecutive orthodontic referrals seen at a consultant orthodontist's clinic were compared and contrasted with the same number seen at each of four specialist orthodontic practices located in the same city, and within 4 miles of the consultant unit. Comparisons were made both on the basis of clinical information obtained from study models and from analysis of referral letters. The consultant sample contained a greater proportion of requests for treatment plans, but there were few differences in terms of the range and severity of the actual malocclusions referred to each of these specialist services. The implications of these findings are discussed in relation to possible future developments of orthodontic services in the U.K.
The daily activity and energy metabolism of pouched mice (Saccostomus compestris) from two localities in southern Africa was examined following warm (25 degrees C) and cold (10 degrees C) acclimation under long (LD 14:10) and short (LD 10:14) photoperiod. There was no differential effect of photoperiod on the daily activity or metabolism of pouched mice from the two localities examined, which suggests that reported differences in photoresponsivity between these two populations were not the result of differences in daily organisation. Nevertheless, there was a significant increase in metabolism at 10 degrees C, irrespective of photoperiod, even though seven cold-acclimatized animals displayed bouts of spontaneous torpor and saved 16.4-36.2% of their daily energy expenditure. All but one of these bouts occurred under short photoperiod, which suggests that short photoperiod facilitated the expression of torpor and influenced the daily energy metabolism of these individuals. As expected for a nocturnal species, the amount of time spent active increased following acclimation to short photoperiod at 25 degrees C. However, there was a reduction in mean activity levels under short photoperiod at 10 degrees C, possibly because the stimulation of activity by short photoperiod was masked by a reduction in activity during bouts of spontaneous torpor. Cold temperature clearly had an overriding effect on the daily activity and metabolism of this species by necessitating an increase in metabolic heat production and eliciting spontaneous torpor which over-rode the effect of short photoperiod on activity at an ambient temperature of 10 degrees C.
The anatomic basis of the facial asymmetry resulting from untreated congenital muscular torticollis is discussed, and an objective system for both clinical and cephalometric assessment and measurement is described. Symmetry is assessed by first defining a true midfacial line, which allows both measurement of existing asymmetry and planning for subsequent surgical correction, and which can be applied to clinical as well as radiologic analysis.
The facial asymmetry which develops in association with untreated congenital muscular torticollis is principally the result of a subcranial torsional rotation of the face toward the affected side. Principles of management are therefore to firstly release the sternomastoid muscle and achieve maximal improvement in head posture, followed by surgical straightening of the face by bimaxillary surgery and septorhinoplasty. The results of this approach in three patients are discussed and illustrated.
Little attention has been directed towards reconstruction of the mandibular condyles in adult patients with rheumatoid arthritis, other than with allogenic implants which are now known to cause serious complications. There is a relatively high incidence of condylar erosion and breakdown in rheumatoid arthritis, often leading to anterior open bite and retrognathia. Costochondral grafting does not appear to have been considered as a logical option for reconstruction, despite its high success rate in many other situations. A case is described of rapid bilateral condylar destruction occurring in a young woman with rheumatoid arthritis, leading to anterior open bite. Reconstruction was undertaken using bilateral costochondral grafts, giving an excellent clinical result which has been maintained over the follow-up period of two-and-a-half years. Radiologically complete healing of severe glenoid fossa erosion has taken place.
All clinicians who administer intravenous sedation should undergo appropriate training according to recognised guidelines. Such guidelines are now established in New Zealand through the joint endeavours of the New Zealand Dental Association, Royal Australasian College of Dental Surgeons, and the Australian and New Zealand College of Anaesthetists. It is essential that there be acceptable staff training and experience, that physical facilities and arrangements for emergency care are adequate, and that parameters for patient selection are adhered to. Adequate knowledge of pharmacology and the therapeutic indications for specific sedative drugs is necessary, and sedation procedures must be undertaken with appropriate monitoring. There are significant medico-legal aspects to this area of dental practice and these should be well recognised by all practitioners.
An investigation was undertaken to assess the reliability of radiographic diagnosis of abnormalities of orthodontic significance in the anterior region of the maxilla from intraoral and dental panoramic tomograph (DPT) views. DPT films of 200 patients were scrutinised by two observers on two separate occasions, who also examined intraoral radiographs of the same patients. Sixty-three of these patients were selected because they had previously been diagnosed as presenting with a defined abnormality of orthodontic relevance, such as supernumerary teeth, absent incisors, etc. The remaining cases had been assessed as depicting normal radiographic appearances. Each radiograph was allocated a unique, randomly selected code number as the only means of identification. It was not possible for the observers to match the DPT to the corresponding intraoral films, and this information was only available to the principal investigator (JWF). Both observers were asked to record the presence or otherwise of any abnormalities at each observation of each radiograph, and to record their findings. The overall level of diagnostic accuracy and reproducibility was fairly high, and in general terms the DPT views were as reliable as the intraoral films with regard to the detection of abnormalities; however, there were significant differences between the observers. It was concluded that in many instances supplementary intraoral films would not contribute any additional information compared to the DPT and that selection criteria should be defined for the former.
Based on the clinical observation that pain is experienced during parotid gland surgery under local anaesthesia, the presence of the sensory neuropeptide substance P (SP) was sought. Using a polyclonal antibody, the presence of SP was demonstrated by an indirect immunofluorescence technique, with rat parotid gland and spinal cord serving as controls. SP-containing neuronal elements occurred around acini, blood vessels and ducts. It is suggested that some of the SP-immunoreactive elements are the unmyelinated and thinly myelinated small diameter (A delta and C) fibres, which are regarded as the peripheral receptors for nociceptive information.
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Mucus-producing adenopapillary carcinoma is a rare neoplasm of the oral cavity. The literature is reviewed and a case described, with histological and ultrastructural findings of a tumour which involved the upper lip and recurred following local excision.
The accuracy of vertical control during maxillary orthognathic surgery was assessed in 45 patients, comparing the use of traditional internal measurements across the osteotomy lines (15 subjects) with measurements between the incisor teeth and an external reference point consisting of a bone screw placed at nasion (two groups of 15 subjects each). Although use of a fixed external reference point can significantly decrease positioning error (p < 0.001), considerable care is required during application of rigid fixation to maintain the correct vertical dimension.
A technique is described which utilizes a light-cured periodontal dressing (Barricaid) in conjunction with the surgical exposure of palatally displaced maxillary canines. The procedure is very quick and simple to perform, with some distinct advantages over alternative methods.
Mandibular fractures are the second most common facial fracture, the majority being the result of interpersonal violence, road traffic accidents, or sports injuries. Although most of these patients attend a hospital, it is not uncommon for patients with these injuries to present first to the general dentist, perhaps complaining of a loose tooth or abnormal bite. A careful history should be taken from the patient in order to identify the possibility of other injuries. Mandibular fractures are rarely life-threatening, although airway difficulties can arise. A systematic approach to diagnosis is essential if fractures are not to be missed, including radiological assessment in two planes at right angles. The initial treatment consists of airway management, control of fracture segments, and pharmacologic management. Most fractures have been traditionally managed by the use of intermaxillary fixation; however, increasing use is being made of open reduction and internal fixation techniques. Occasionally, general dentists are involved in the post-operative care of the patient following definitive management.
Mandibular fractures are the second most common facial fracture. The usual causes are interpersonal violence and motor vehicle accidents (MVA). Nearly all cases present to an emergency department for initial management. They are rarely life-threatening injuries and must assume low priority in the initial assessment and management of the severely traumatized patient. Following any resuscitation and exclusion of other significant injuries, a clinical and radiologic diagnosis of the facial injuries should be undertaken including assessment of the fractured mandible. Initial therapy should be directed at temporary immobilization and pharmacologic treatment, followed by referral for appropriate definitive care.
Lesions induced in hamster cheek pouch using dimethylbenz(alpha)anthracene were studied by transmission electron microscopy and compared with normal tissue. Features regarded as suggestive of progression towards malignancy were: increased numbers of membrane-bound vesicles in basal cells, gaps in the lamina densa associated with widening of the lamina lucida and an irregular epithelial-connective tissue junction, the presence of cerebriform cells and frequent close association of 2 or more intra-epithelial cells (lymphocytes, cerebriform cells, Langerhans cells).
The oral and facial manifestations of pycnodysostosis (Maroteaux-Lamy syndrome) are reviewed, and illustrated by a case in which the presenting feature was delayed and ectopic eruption of permanent teeth.
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