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Biomedical subjects

D W Lewis

Publications and source records attributed to D W Lewis.

At least 91 records · Page 5Linked to original sources
PubMed1977

Epidemiology of dental caries in the premolar and second molar teeth of Scottish children in relation to pits and fissures.

To evaluate the potential benefits from elimination of dental caries in the fissures of teeth, surface patterns of decay were calculated for all surfaces of the premolar and second molar teeth of 98 children followed longitudinally for 5 years, between ages 11 and 15 years. Tooth eruption and susceptibility were also examined in relation to the administration of sealant programs. The children who were part of the control group of a fluoride dentifrice study on the Scottish Isle of Lewis, had low exposure to fluorides, high caries attack and very low restorative treatment levels; so true surface caries distribution was not masked. Variation in tooth eruption and susceptibility suggested that semiannual applications of preventive agents at each year age 10 through 15 might be required. Using hypothetical percentage reductions, the substantial potential benefits for caries control of the early use of completely retained occlusal, as well as buccal and lingual (molars), fissure sealants are conclusively demonstrated. However, improvements in the present technology of fissure sealants and their application are apparently required if these benefits are to be extended to large groups of children.

Adolescent↗
PubMed1976

Effect on caries of self-application of a zirconium silicate paste containing 9% stannous fluoride.

A 2-year clinical trial was conducted using an adolescent population from a low-fluoride area to evaluate the anticaries effect of self-applications of zirconium silicate paste containing 9% stannous fluoride. tthree study groups totaling 464 children, with an initial average of 12.8 years, completed the study. The control group brushed with a non-fluoride zirconium silicate paste (tzircate Prophylaxis Paste) once each year: the first experimental group brushed with zirconium silicate paste containing 9% stannous fluoride (Zircate Treatment Paste) once each year; and the second experimental group brushed every 6 months with Zircate Treatment Paste. After 2 year, the DMFT and DMFS increments were virtually identical for the control group and the group that received one application of fluoride paste per year. The group that received two applications of fluoride paste per year had a DMTF increment that was about 24% less than that of the control group; however, the DMFS increment was only 5% less. These differences were not statistically significant at the P=.05 level.

Adolescent↗
PubMed1976

The effect of external pressure on skin temperature distribution by thermography.

1) Serial thermograms were taken after the application of various intensities and durations of localized pressure on the medial surface of the human forearm. 2) Thermal response of the body surface to localized pressure was quantified. 3) It was found that usually a time period of between 1 to 3 minutes elapsed before the body surface attained a maximum elevation of temperature from the time the localized pressure is removed. 4) It was found that increased intensity of pressure (5 psi vs. 3 psi) and longer duration (20 minutes vs. 10 minutes) caused larger thermal responses. 5) It is suggested that high resolution medical thermography may eventually become a useful tool in the fitting of prosthetic and orthotic devices and for the prediction of pressure sores formation so prophylactic measures can be started immediately on immobilized patients.

Adult↗
PubMed1975

A small pliable humidity sensor, with special reference to the prevention of decubitus ulcers.

In an investigation of some of the external causes of decubitus ulcer, a small flexible sensor has been developed as a clinical device to measure the relative humidity (RH) of the environment between the patient and the surface on which he lies. The sensor (described in detail) can indicate RH in the range of 20 to 90 per cent by a color-matching method (chemically impregnated circles); accuracy is within 5 to 10 percent. In a preliminary study on 28 patients, the readings showed that RH was higher in the sacral region than in the scapular region, and higher for patients who were inactive than for those who were active. The device was well accepted by both patients and nurses.

Dermatology↗
PubMed1975

Thermographical investigation of decubitus ulcers.

1. Posterior body reference thermograms indicate that in general a similar thermal body pattern of humans does exist. 2. The buttocks, hips, and thighs of a nude subject are thermally cool regions, possibly indicating poor vascular circulation and/or large fat concentrations. 3. Thermograms of the same anatomical area on the same subject under controlled environmental conditions are thermally similar. 4. The scapular region is from 1 to 2 deg F hotter than the sacral region for subjects reclining on Mylar. 5. The 1 deg temperature differential thermograms and the reference thermogram while the subject is on Mylar, in many ways, denote the geometrical shape of the underlying bone structure, especially the bones of the scapulae and sacrum. 6. On the degree temperatue differential thermograms, the anatomical regions most accused of being decubitus ulcer prone are the regions of highest temperatures: the scapulae, sacrum, elbows, and calves. 7. During reactive hyperemia, the visible red flare over the sacrum and coccyx becomes very intense in the first few minutes and then gradually diminishes. The thermal flare persists longer than the visible flare. The extended duration of the thermal flare over the visible red flare is attributed to a continued local elevated metabolic tissue rate caused by the previous engorgement of blood. 8. The thermal mottling seen in the first minute after releasing the load is believed to have been caused by the rapid infusion of blood and the dilation of affected vessels responsible for making up the blood flow debt which occurred during the period of ischemia. 9. A posterior body heating effect noticed immediately after the subject left the Mylar film has been attributed to the insulative qualities of the film. The cooling effect is more difficult to explain, but it is thought that the higher than average room temperature caused an increased evaporative cooling rate response of the two subjects either before getting off the film or immediately after getting off and therefore reduced the temperature of the skin. 10. The maximum reactive hyperemic temperature difference, the difference between the initial standing reference thermogram and the maximum flare temperature observed during tissue hyperemia, may be as high as 12 deg F. 11. Males on the average have larger flare patterns than females, 5.7 in.2 and 4.7 in.2, respectively. The flare areas were computed from thermograms taken 2 to 3 minutes after off-loading of tissue. 12. With the average distance from the buttock's fold to the highest and lowest thermal flare indication being lower for females (3.2 and 5.9) than for males (3.8 and 6.4), a relationship between the site or decubitus ulcer formation and the pelvic bone structure of the sexes may well exist. 13. No two thermal flare patterns are similar either in size or in shape. Thermal flare patterns occur along the centerline of the body at the sacrum and coccyx level. 14...

Adolescent↗