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Biomedical subjects

D Poswillo

Publications and source records attributed to D Poswillo.

At least 19 recordsLinked to original sources
PubMed1989

Obtaining consent to oral and maxillofacial surgery.

The question of whether or not a patient has consented to treatment has recently become significant to all who practise oral and maxillofacial surgery. It is often linked to professional negligence when the outcome differs from the patient's perception or expectation of the operation. Consent may be oral or written, applies to referred patients and all those with physical and mental handicap and religious restrictions. Examples of procedure in discussing consent assist the surgeon to inform without creating fear. Knowledge of the benefits of informed consent and current legal opinion assist the oral and maxillofacial surgeon to avoid the pitfalls of failure to inform.

Adolescent↗
PubMed1988

The aetiology and pathogenesis of craniofacial deformity.

Craniofacial malformations have been recorded since time immemorial. While observational studies have assisted in the recognition of syndromes, little light has been shed on the causal mechanisms which interfere with craniofacial development. Animal studies in which malformations occur spontaneously or have been induced by teratogenic agents have permitted step-by-step investigation of such common deformities as cleft lip and palate. The role of the ectomesenchymal cells of the neural crest and the possible phenomenon of disorganized spontaneous cell death are described in relation to lip clefts. The factors associated with isolated cleft palate, Pierre Robin syndrome and submucous clefts are described by reference to animal models. The haemorrhagic accident preceding the onset of craniofacial microsomia is discussed as is the distinctly different phenomenon of disturbance to the migration or differentiation of neural crest cells in the pathogenesis of Treacher Collins syndrome. The more severe anomalies of the calvarium such as plagiocephaly, Crouzon and Apert syndrome still defy explanation, in the absence of an appropriate animal system to study; some thoughts on the likely mechanism of abnormal sutural fusions are discussed.

Animals↗
PubMed1983

Conservative management of degenerative temporomandibular joint disease in the elderly.

Degenerative arthropathy and rheumatoid disease produce significant morbidity in elderly dental patients. Clinical and radiographic examination usually indicates the nature and extent of the disease in the temporomandibular joints and provides the basis for graduated treatment. Conservative measures are generally more acceptable and most successful in the elderly patient with pain, limitation of opening and grating of the joint. Acute-onset arthritis is relieved by local anaesthetics, non-steroidal anti-inflammatory drugs and occlusal adjustment. Occasionally, intra-articular steroids are needed; these provide prolonged relief from pain and stiffness. Remedial exercises, in conjunction with physical therapy, should be continued after resolution of the acute attack or used as primary treatment for chronic arthropathy. A small proportion of cases remain resistant to conservative treatment; blind condylotomy (surgical sectioning) of the affected condylar neck is a safe, effective procedure for refractory cases which do not respond to the conservative regimen described. This procedure may be used for degenerative arthropathy and also for chronic dislocation which has failed to respond to peri-articular injection of sclerosing agents. Rheumatoid disease in the jaw should be treated in conjunction with the medical therapist when other joints are involved.

Adrenal Cortex Hormones↗
PubMed1981

The ear deformities in mandibulofacial dysostosis (Treacher Collins syndrome).

Bilateral conductive deafness is common in mandibulofacial dysostosis with or without atresia of the external auditory meatus. This deafness is due to a wide range of deformities of the ossicular chain associated with a characteristic reduction in the size of the middle ear cavity. The attic and antrum are particularly affected and usually have a slit-like appearance on coronal section tomograms. The inner ear is essentially normal. The tomographic appearances of 44 ears from 22 patients with mandibulofacial dysostosis are described as well as the operative findings in 14. These were correlated with induced ear deformities in an animal model that had features characteristic of human mandibulofacial dysostosis. A review of the findings in the animal model suggests a very close correspondence with the human ear anomalies described at radiological investigation, operation and post-mortem examination. The lesions are largely symmetrical and this, with the characteristic slit attic, helps to differentiate mandibulofacial dysostosis from lesions with different aetiology but similar features such as facial microsomia. The prospects for surgical correction of the deafness in mandibulofacial dysostosis range from very good in mild cases with ossicular discontinuity, to poor where there is severe atresia. The importance of tomograms at an early age is stressed.

Animals↗
PubMed1981

A pilot study on the effect of alteration of the suprahyoid muscles on the growth of the marmoset monkey.

A pilot study was undertaken to determine the effect, if any, of alteration of the suprahyoid muscles on mandibular growth in the marmoset. It was postulated that releasing the attachment of the digastric and geniohyoid muscles at their junction with the mandible might produce a growth change in the rotation pattern of mandibular growth. Similarly, shortening these muscles might produce a different but significant growth change. Ten animals were used, five of which were controls. Two animals had their suprahyoid muscles sectioned, and three others had their suprahyoid muscles shortened by plication. The animals were examined with cephalometric radiographs at the commencement of the experiment and at specific intervals thereafter until they reached maturity (approximately 1 1/2 years of age). The results indicate that releasing the digastrics and the suprahyoids at the mandible causes no significant change in the length of the mandible. Shortening of the suprahyoids through plication, however, appears to result in a notable change in the mandible and possibly the face. This study suggests that further research in this area may be fruitful in producing a primate model with a' retruded genial area or a tongue protrusion by plication or otherwise shortening the suprahyoid muscles.

Animals↗
PubMed1977

Effect of intra-articular corticosteroid injections on primate cartilage.

An attempt was made to ascertain whether intra-articular corticosteroids exert a harmful effect on primate cartilage. The knee joints of 10 Macaca irus monkeys were subjected to either one, two, or six injections of 20 mg methyl prednisolone or an equal number of control injections over a 12-week period. Minor degenerative changes of many femoral condyles were shown by India ink staining and by a system of histochemical grading. Changes in the joints injected with corticosteroid were not significantly different from those seen in control joints. The findings were in striking contrast to the severe degeneration reported by others in rabbit joints injected with corticosteroid. The experiment did not support the contention that intra-articular corticosteroids invariably have a deleterious effect on primate cartilage.

Animals↗
PubMed1975

The pathogenesis of the Treacher Collins syndrome (mandibulofacial dysostosis).

Numerous synonyms have been used to describe syndromes affecting structures derived from the first and second branchial arches. These conditions are most conveniently grouped into the asymmetrical anomalies of hemifacial microsomia and the symmetrical syndrome of mandibulofacial dysostosis. By examination of animal models of these conditions it can be demonstrated that the pathogenesis is distinct but different for each group. The characteristic facies of mandibulofacial dysostosis suggests a mechanism of malformation which operates early in embryogenesis, acting uniformly on parts which are derived from neural crest cells. In the serial examination of a phenocopy of mandibulofacial dysostosis, induced in the rat by the teratogen vitamin A, focal death of pre-otic neural crest cells is observed to occur, creating both a spatial rearrangement of the developing ears and a paucity of ectomesenchyme in the first and second branchial arches. The result of these deviations from normal morphogenesis is the development of a facial skeleton which is symmetrical but distinctly different in form from that in the normal animal. Microscopic study of the induced ear and jaw defects revealed that the animal model was closely comparable in all respects to human mandibulofacial dysostosis. The specific nature of the interaction between teratogen and migrating neural crest cells is not yet clear; nor is it known whether these cells are attacked before or after their specific destination is determined. The greater part of the damage is inflicted in a general fashion and leads to symmetrical abnormal development. Minor examples of dyssymmetry do occur, however, in the animal model and man, but these are compatible with the hypothesis of a pathogenetic mechanism which is initiated centrally and symmetrically but modified locally at a later stage. A description of the pathogenesis of these two conditions, scientific predictions can be made with respect to the timing and technique of reconstruction of the orofacial defects, and the effects of surgery on growth and development.

Abnormalities, Multiple↗
PubMed1975

Evaluation, surveillance and treatment of panoral leukoplakia.

Leukoplakia is well-recognised as a premalignant condition of the oral mucosa. Despite many attempts to produce definitive laboratory tests for the prediction of those cases of premalignant leukoplakia which may undergo malignant transformation, there is as yet no fool-proof method of clinical and laboratory assessment. The problem is nowhere more manifest than in the management of panoral leukoplakia, especially in frail, elderly and apprehensive patients. In such cases the selection of sites for biopsy and treatment is often more empirical than logical. The introduction of cryosurgical techniques for the treatment of leukoplakia has enabled the surgeon to eradicate panoral white patches in a more conservative fashion. The application of a diagnostic nuclear staining test using toluidine blue dye, coupled with local exfoliative cytology, has provided a system for evaluation and surveillance of panoral leukoplakia which is clinically simple and at least as reliable as any predictive test previously described.

Aged↗
PubMed1975

Hemorrhage in development of the face.

Focal hemorrhages, early in embryogenesis, may play a significant part in the pathogenesis of specific malformations. Animal models of hemifacial microsomia and thalidomide-induced otomandibular dysostosis are described; the causal mechanism of malformation appeared to be closely related to the formation of a hematoma at the time of development of the stapedial arterial systems. The effects of the hematoma on morphogenesis are described, and the changes observed in the animal models compared with similar anomalies in man.

Abnormalities, Drug-Induced↗