Biomedical subjects
T A Parr
Publications and source records attributed to T A Parr.
Oral mucosal screening as an integral part of routine dental care.
The principal aim of this study was to assess the feasibility of conducting a systematic examination of the oral mucosa, as an integral part of the routine dental check-up and in conditions comparable with those in NHS dental practice. A total of 1949 individuals, who were already registered as patients with an industrial dental clinic, were invited to attend for an oral screen as part of their dental examination. Of these, 1947 patients agreed to participate and were also asked to complete a 'habits' questionnaire relating to their tobacco and alcohol use. A systematic examination of the oral mucosa was undertaken as part of the routine dental inspection and mucosal lesions were recorded as either a positive or negative screening result. Lesions included as a positive result were those which may be associated with early cancer or precancer. Four patients (0.2%) were considered to have a positive screening result and these were referred for specialist evaluation. Of these, two had tobacco-related leukoplakia, one had oral lichen planus and the other had an early squamous cell carcinoma. This study has confirmed that a systematic and thorough examination of the oral mucosa can realistically be carried out as part of the routine dental inspection in NHS dental practice.
'An investigation into sugar-containing and sugar-free over-the-counter medicines'.
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The effect of lesion characteristic on remineralization and model sensitivity.
A major criterion for assessing the value of any experimental model in scientific research is the degree of correspondence between its results and data from the real-life process it is designed to model. Intra-oral models aimed at predicting the anti-caries efficacy of toothpastes or other topical treatments should therefore be calibrated against treatments proven to be effective in a caries clinical trial. For this to be achieved, it is necessary that a model with high sensitivity be designed, while at the same time retaining relevance to the process to be modeled. This means that the effects of the various experimental conditions and parameters of the model on its performance must be understood. The purpose of this paper was to assess the influence of two specific factors on the performance of an in situ enamel remineralization model, which is based on human enamel slabs attached to partial dentures. The two factors are initial lesion severity and origin of enamel sample. The results indicated that initial lesion size affected whether net remineralization or net demineralization occurred during in situ treatment. Samples with an initial range of from 1500 to 2500 (delta Z) tended more toward demineralization than did samples with delta Z greater than 3500. This means that treatment groups must be well-balanced with respect to initial lesion size. Differences in initial demineralization severity between different tooth locations must also be considered so that systematic treatment bias can be avoided. The solution used in the model discussed here is based on a balanced experimental design, which allows this effect to be taken into account in the data analysis.
The effect of study design on in situ treatment of carious enamel lesions.
The aim of this exploratory study was to investigate the influence of several factors on changes in the mineral content of carious enamel lesions treated in situ. The study involved 36 adult volunteers who used either a non-fluoride toothpaste or one of two fluoride toothpastes (1000 or 1500 ppm F). Human enamel specimens were prepared and attached to partial dentures as described previously (Schäfer, 1989) and treated in situ for between three and six weeks. The mineral content of lesions was determined by microradiography and computerized densitometry. The factors investigated in this study included study length, frequency of treatment, trial design, patient compliance, patient diet, and previous caries experience of the patient. The effects observed were small, relative to that of the treatment, and not statistically significant (p greater than 0.05). However, the trends in the data were all as would be intuitively predicted. Study duration correlated positively with observed lesion mineral content. Lesions worn by panelists using a fluoride toothpaste for six weeks contained greater levels of mineral with respect to placebo than did those in panelists on a three-week study. The residual variations in the three phases of the study were found to be similar, suggesting that there is no advantage in these studies having a cross-over design. Brushing frequency also correlated positively with observed lesion mineral content, with panelists brushing three times per day with a fluoridated dentifrice having lesions with greater levels of mineral, with respect to placebo, than those brushing twice per day. Overall, no clear relationship between reported diet and changes in lesion mineral levels was apparent.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparison between evaluation methods for the anti-caries efficacy of monofluorophosphate-containing dentifrices.
A comparison is described of three methods of preclinical assessment of potential anti-caries efficacy for topical fluoride treatments. Methods are compared using dentifrices containing 1,000, 1,500 and 2,500 ppm F as sodium monofluorophosphate (SMFP). These formulations have been shown elsewhere to give a statistically significant dose response of increasing anti-caries efficacy [Stephen et al., 1988]. An in situ enamel insert model, oral fluoride pharmacokinetics and F uptake to demineralised enamel are all shown to correlate with clinical efficacy for the test dentifrices studied.