School of Oral Health Sciences
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Item A comparative sem study of keratinized and non-keratinized oral mucosa of the vervet monkey(1981) Grossman, E. S.; Cleaton-Jones, P. E.Scanning electron microscopy has revealed that the surfaces of keratinized and non-keratinized oral epithelial cells have characteristic features which enable these tissue types to be readily distinguished. These features include pits, villus-like projections and ridge-like folds called microplications. The origin and functional significance of these structures is not known, although several hypotheses have been proposed. Microplications have been interpreted as a reserve area for cell stretching but further studies have yielded conflicting results. Cellular interdigitation resulting from the microplications may aid adhesion between the stratified epithelial cells. This view has been supported by subsequent investigations of superficial epithelial cells. The situation in the deeper cell layers is not entirely clear.Item Hypocalcification and hypoplasia in primary teeth of pre-school children from different ethnic groups in South Africa(1989) Hargreaves, J. A.; Cleaton-Jones, P. E.; Roberts, G. J.; Et alA study was completed in 1985/86 which examined the dental health of pre-school children from different ethnic groups and communities in South Africa: rural black, urban black, urban colored, urban Indian, and urban white. Enamel defects were recorded in primary teeth by use of the HHI, an index developed to measure hypocalcification and hypoplasia of enamel. The findings showed that colored children had the greatest number of enamel defects. The teeth most commonly affected were the maxillary anterior teeth and mandibular molar teeth. It is suggested that further epidemiological studies utilizing the HHI should be undertaken in pre-school children, especially from developing countries, to gain more information on the causes of enamel defects in the primary dentition and the possible use of such findings to predict nutritional health of individuals.Item Hypocalcification and hypoplasia in permanent teeth of children from different ethnic groups in South Africa assessed with a new index(1989) Hargreaves, J. A.; Cleaton-Jones, P. E.; Williams, S. D. L.A new descriptive index, the HHI (hypocalcification-hypoplasia index), is described for comparing enamel defects in groups of people. The index was used in a study completed in 1986, in which 1251 11-year-old children from different ethnic groups resident in South Africa were examined: 210 rural black, 203 urban black, 206 urban colored, 426 urban Indian, and 206 urban white. The index can be used as a screening examination, and the results from these different ethnic groups are presented.Item An ethical dilemma. Availability of antiretroviral therapy after clinical trials with HIV infected patients are ended(1997) Cleaton-Jones, P. E.Guidelines on good clinical practice for drug trials clearly state that ethics committees must ensure that the safety, integrity, and human rights of the subjects participating in a particular trial are protected.1 Fundamental concepts are informed consent and risk or benefit to participants in a trial. For many clinical trials, ethical clearance is straightforward but those involving people infected with HIV generally are not. Here, we are dealing with a condition that is presently incurable with variable progression, drug treatment is expensive, and emotions run high. These matters are common to all countries, but those of us living in Africa have an added burden–Third World conditions and an estimated 13 million people infected with HIV, usually from heterosexual sex.2 In South Africa the most recent published results for the fifth unlinked anonymous national HIV survey show that HIV infection in women attending antenatal clinics has risen from a national average of 1.35% in 1991 to 7.57% in 1994.3 In some parts of the country the rate is as high as 14.35% and is increasing.3 Because of a shortage of resources, antiretroviral drugs for treating HIV are not provided by South African public health services: these are available only in the private sector at great expense. Given this high prevalence of HIV it is understandable that multinational drug companies are attracted to carrying out trials in our country, with its combination of a large infected population and proved medical expertise. Ethics committees are currently receiving trial protocols for combinations of drugs from such companies. All protocols provide for the free supply of trial drugs for a specified period, usually two to three years, for patients satisfying the inclusion criteria. The trials are well designed and comprehensive, but there is no guarantee that the drug treatment will be continued beyond the end of the trial. Therein lies the problem. South African ethics committees use guidelines on ethics for medical research provided by the South African Medical Research Council.4 Comprehensive as these are, they do not solve the following dilemma. What is the responsibility of a trial sponsor to a trial subject who responds to treatment that will not be available after the end of the trial? With most diseases this is not a problem since alternative treatments are available. However, when no other treatment is available to trialists what should be done? If a patient infected with HIV responds to the test drugs, may one ethically withhold the drugs at the end of the trial, thereby depriving the person of benefit? My committee's opinion up to the present has been that it is not ethical to do so and that such trial subjects must continue to receive the antiretroviral treatment after the trial ends until they cease to benefit or are enrolled into another trial. Naturally, most companies have not received this opinion with joy. Their argument is that informed consent, which clearly states the length of a trial, takes care of the problem. In theory this is correct, but South Africa has large numbers of people insufficiently educated to understand the implications of what they are consenting to. In early trials, when monotherapy was the rule, many companies complied with our requirement, but combination therapy has altered company policy. Companies often must purchase another manufacturer's drug to use in conjunction with their own. As a compromise, companies are generally prepared to provide their trial drug until it is no longer under development or is commercially available or they will provide zidovudine alone. Since combination therapy is the current optimal treatment,5 6 can ethics committees allow patients to revert back to a less effective treatment? Furthermore, even if a drug becomes commercially available, is it ethical to halt treatment knowing that neither the health service nor trial subject can afford it? Investigators fall into two clear camps. Some will not undertake trials unless there is an arrangement for their patients to receive drugs long term or to be enrolled in subsequent trials. Others know that their patients would normally receive no treatment at all, so two to three years of treatment is of some benefit at least and may buy time for future breakthroughs. A further complication is the variation in policy of ethics committees. Our committee, established in 1966, is the oldest and most experienced in South Africa and is known to be conservative. Protocols not accepted by us, we know, have been readily approved in the private sector or at other institutions. To be fair to all concerned we have sought personal opinions from research coordinators in HIV trial groups in Canada and Australia. In Canada continuation of drug treatment beyond the trial is expected, but this is simpler because a drug company can continue to supply its own drug to be added to the antiretroviral treatment available from the public health services. In Australia it is accepted that drug companies are unlikely to provide long term treatment, and colleagues there believe that monotherapy, with at least a double nucleoside, after completion of a trial is acceptable when no other treatment is available. Realistically, the level of illness required for inclusion into trials is such that many subjects may not survive past the trial period. Surely, agreement can be made on a response to the trial drugs so that only those responding may continue treatment; those not responding may be taken out of the trial to free resources for the responders beyond the trial. This has been debated at length in our committee with investigators, trial sponsors, and potential subjects. The most strident voices of all are those of patients infected with HIV, who feel that the decision to participate in a trial is theirs alone, not that of an ethics committee acting in a paternalistic manner. But ethics committees have to ensure that patients are not exploited and that benefit outweighs risk.Item The effect of frozen irradiated bone homografts on the healing of defects in the mandible and femur of the rat(1971) Cleaton-Jones, P. E.; Retief, D. H.; Maier, G.1. The effects of frozen irradiated homogenous bone grafts on the healing of circumscribed defects in the mandibles and femora of forty albino rats have been studied. 2. The grafts were well tolerated by the host animals and did not appear in any way either to stimulate or to inhibit osteogenesis. The rate of healing of the defects containing the homografts compared favourably with that of the control defects.Item Airway status in civilian maxillofacial gunshot injuries in Johannesburg, South Africa(2002) Tsakiris, P.; Cleaton-Jones, P. E.; Lownie, M. A.BACKGROUND: Airway management of the maxillofacial gunshot injury constitutes a critical decision and an area that requires review in the context of civilian injuries. Most of our knowledge is extrapolated from military experience, which constitutes a different trauma patient group. This paper reports a retrospective survey of airway status in relation to maxillofacial gunshot injuries. The objective is to correlate clinical findings with treatment decisions. METHODS: A survey was done of 11,622 archived maxillofacial surgery records (1987-1992) in the three academic hospitals in Johannesburg. RESULTS: There were 211 maxillofacial gunshot injuries, for which 92 patient records had sufficient detail for inclusion in the analysis. The typical patient was a black male aged 20-29 years, shot with a low-velocity bullet of 0.38 calibre, admitted to hospital the day of the injury, operated on within 4 days, and discharged 4 days later. The airway was threatened in 20/92 cases at admission; 12/20 cases were treated with oro-or nasotracheal intubation, and 9/12 later had elective tracheostomies; 8/20 needed immediate surgical airways, 5 tracheostomies and 3 cricothyroldotomies (all later converted to tracheostomies). Three of thirty-seven patients with normal airways on admission later required emergency tracheostomy. CONCLUSIONS: An abnormal airway was significantly more likely after a high-velocity injury, and when the tongue, floor of mouth, midline or bilateral facial skeletal bones were involved.Item Delayed passive eruption - A predisposing factor to Vincent's Infection?(1974) Volchansky, A.; Cleaton-Jones, P. E.Item Rampant caries and labial caries - synonyms?(1977) Richardson, B. D.; Cleaton-Jones, P. E.Item Activation analysis in biological material(1975) Turkstra, J.; Retief, D. H.; Cleaton-Jones, P. E.Item Clinical, histological and microbiological study of hand-excavated carious dentine in extracted permanent teeth(2003) Bönecker, M.; Grossman, E.; Cleaton-Jones, P. E.; et alChanges in cultivable flora in dentine samples collected before and after hand excavation were examined in association with clinical status of the cavity surface, light microscopy and scanning electron microscopy (SEM). Thirty-five extracted permanent molar teeth with an occlusal caries lesion were excavated with hand instruments according to the atraumatic restorative treatment (ART) approach. Excavation pressure, dentine colour and consistency were recorded at the dentine-enamel junction (DEJ) prior to carious dentine removal and at the cavity floor after the final excavation; a microbiological sample of dentine was taken at both stages. Twelve restored teeth; six with positive and six with negative bacterial growth on the second sample, were selected for light microscopy and SEM. The hand-excavation removed tooth structure was soft, irreversibly damaged, dark and highly infected. Hand excavation reached dentine of increased hardness with a more normal colour to provide a sound structural base for restoration. Light and SEM examination of the cavity floor showed infected dentinal tubules in all 12 teeth examined. Linear logistic analysis showed a statistical association between light-yellow dentine on the cavity floor and an absence of bacterial growth (P = 0.006). This short-term in vitro study showed that caries-producing bacteria remained in dentine close to the cavity floor in 26/35 teeth despite clinical observations that indicated a suitably prepared cavity floor.