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Biomedical subjects

P Cleaton-Jones

Publications and source records attributed to P Cleaton-Jones.

At least 91 records · Page 5Linked to original sources
PubMed1982

Correlative light microscopic and scanning electron microscopic study of completely and incompletely orthokeratinized rat oral epithelium.

Using light microscope (LM) and scanning electron microscope (SEM) a study of the surface morphology of rat oral epithelium was undertaken. A good correlation was found between the LM and SEM findings in the demonstration of the characteristic differences in surface structure between completely and incompletely orthokeratinized areas of the rat oral epithelium. Completely keratinized epithelium (hard palate and attached gingiva) shows a surface layer of orderly arranged, closely approximated and overlapping cells. The individual cell surface shows a honeycomb pattern of interconnecting ridges surrounding depressions or micropits. Incompletely keratinized epithelium (buccal mucosa, alveolar sulci, gingival crest and interpapillary area of the dorsum of the tongue) shows a very uneven, corrugated surface layer. There is considerable loss of cell cohesion with the formation of wide intercellular clefts. The individual cell surface is characterized by microplications of irregular size and arrangement. The findings of the present investigation are discussed in the light of an idea previously put forward by the authors that a correlation exists between surface morphology of the keratinized rat oral mucosa and colonization and penetration of Candida organisms in experimental candidosis.

Animals↗
PubMed1981

Comparison of three anaesthetic scavenging devices using cuffed and noncuffed nasal endotracheal tubes during dental anaesthesia.

During maxillofacial and oral surgery the effect of three anaesthetic scavenging devices used with cuffed and non-cuffed endotracheal tubes was investigated. All the devices produced reductions in nitrous oxide concentrations in the breathing zone and peripheral air, ranging from 36% to 76%. Of the three devices evaluated, the Stellenbosch valve produced the greatest reduction in pollution compared with the control.

Air Pollution↗
PubMed1981

Sweets, snacks, and dental caries: South African interracial patterns.

Sucrose has been thought to cause dental caries; sweets and snacks being primarily responsible, together with plaque and their respective interactions. Dietary questionnaires revealed that in 3 to 5 yr olds, protein in black, colored, Indian, and white groups provided 12 to 15% of total intake, fats 10 to 17%, and carbohydrates 69 to 78%. At 16 to 17 yr old, patterns remained essentially similar. Sucrose provided about one-quarter of intake, sweets and snacks less than one-tenth, but dental caries prevalence increased rapidly from black to white. This raised several questions regarding current concepts of caries causation. Are genetic, immunological and other dietary factors also responsible for caries levels experienced?

Adolescent↗
PubMed1980

Early and late scavenging of anaesthetic gases.

The effectiveness of two waste gas scavenger devices, the Carstens box and the Ventex apparatus, with regard to nitrous oxide pollution was studied under comparable conditions in an operating theatre. The scavengers were brought into use in the early and late stages of induction of anesthesia, and nitrous oxide concentrations in the breathing zone and theatre peripheral air were measured. Both scavengers reduced nitrous oxide pollution at the sampling points. Similar reductions in nitrous oxide pollution in the breathing zone were obtained with both scavengers, but the Carstens box was more effective in reducing nitrous oxide pollution in the peripheral air.

Air Pollution↗
PubMed1980

Patterns of tooth vulnerability to caries in South African high school pupils.

Caries prevalence and distributions were studied in 761 South African high school pupils aged 17 years in four ethnic groups, living in urban (low F) and rural (low and high F) areas. Mean DMFT values were significantly higher among White pupils than all other groups. Comparison of mean DMFT among the Black pupils showed that urban Black dwellers had a significantly higher score than rural pupils when caries-free individuals were included in the analysis, but not when scores for only those with a DMFT of 1 or more were compared. No significant differences were found between the DMFT values of Black rural pupils living in high or low fluoride areas. Among Black rural pupils, dental caries was approximately three times more common in permanent second molars compared with permanent first molars. In urbanized Black, Coloured, Indian and White subjects, the molars were approximately equally affected.

Adolescent↗
PubMed1980

Effects of low concentrations of nitrous oxide on rat fetuses.

The long-term inhalation of air polluted with nitrous oxide has been implicated in spontaneous abortions and fetal abnormalities in operating room personnel. Studies with 1% and 0.5% N2O in air have confirmed the adverse effects of dilute concentrations of N2O in pregnant rats. The present study was designed to determine the threshold concentration of nitrous oxide necessary to produce adverse responses in pregnant rats. Wistar albino rats were mated in an environmental chamber and conception confirmed by vaginal smears. Immediately thereafter, the rats were randomly divided into control and experimental groups. The control rats were exposed for 19 days to oil-free compressed air in an environmental chamber at a flow rate of 8.5 air changes per hour. Experimental animals were exposed continuously under identical conditions to concentrations of 0.0, 0.1%, 0.5%, or 0.025% N2O. On day 19 the gravid rats were killed. The corpora lutea of pregnancy were counted and related to the number of fetuses in the uterus. Fetuses were fixed, cleared, and their skeletons stained with alizarin red. Litter size, frequency of fetal resorption, and fetal crown rump measurements were significantly different following exposure to 0.1% N2O than they were in control rats or in rats exposed to 0.05% or 0.025% nitrous oxide, neither of which had any fetal effects. The suggested threshold level of 30 ppm (0.03%) N2O in humans may be unrealistically low.

Abnormalities, Drug-Induced↗
PubMed1979

Evaluation of driving skills after brief exposure to nitrous oxide.

The driving skills of 10 dental students were evaluated on three occasions on a driving simulator after exposure to air and 50% and 70% nitrous oxide in oxygen. Errors increased after exposure to nitrous oxide and were statistically significant during the middle of the test period. Driving after short exposure to nitrous oxide appears inadvisable.

Adult↗
PubMed1979

Clinical effects of nitrous oxide and oxygen mixtures at sea-level and at 1700 metres altitude.

The effects of nitrous oxide, at sea-level and at an altitude of 1700 m, were assessed on a subjective and objective basis. Only marginal differences were shown between the effects of the gas at sea-level and 1700 m. Since consciousness was impaired with 60 and 70% nitrous oxide it is suggested that the use of Entonox-oxygen mixtures should be considered for single-handed operators.

Adult↗
PubMed1979

A 3-year longitudinal study of the position of the gingival margin in man.

The position of the gingival margin of the incisor and canine teeth, indicated by clinical crown height, was measured using a standardised photographic technique, in 30 dental students over a 3-year period. There was a progressive increase in mean clinical crown height during this period, suggesting that continual passive eruption of the teeth was occurring. There was a significant slowing in the rate of change over the period 1975-1977 for tooth 33, the reason for which is unknown.

Adolescent↗