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Biomedical subjects

K W Stephen

Publications and source records attributed to K W Stephen.

At least 109 records · Page 6Linked to original sources
PubMed1980

Factors determining the passage of drugs from blood into saliva.

1. Following single oral dosing of ampicillin, cephalexin, tetracycline, erythromycin estolate, clindamycin and rifampicin to six normal volunteers, antibacterial activity was measured at 1, 3 and 6 h in serum, gingival fluid and minor gland saliva from all subjects and in parotid and submandiabular saliva from three. 2. pH values of all gingival fluid and saliva specimens were noted. 3. Partition coefficients between n-octanol and water were measured for erythromycin, clindamycin and rifampicin. Published data were used for ampicillin, cephalexin and tetracycline. 4. All antibiotics, but particularly rifampicin, were detected in gingival fluid. Only rifampicin and to a lesser degree, clindamycin were present in the other salivary constituents. 5. In studies of secretion of drugs in saliva, both the physico-chemical characteristics of the drugs and the physiological differences between individual salivary components should be considered. 6. Parotid saliva samples are likely to be of greatest value.

Adult↗
PubMed1980

Studies on the setting behaviour of sealants using a new acoustic method of determining set.

An acoustic method has been used to compare the setting behaviours of three chemical and three u.v. activated sealants. The setting rates of the u.v. sealants were found to have similar sub-linear dependences on the applied u.v. intensity. However, considerable differences in the rates of set of these materials were noted when the same u.v. intensities were applied. Adjusting the composition of one of the sealants (Alphaseal) increased the penetration of the u.v. radiation, resulting in a ten-fold improvement in the setting rate. Suitable exposure times and the intensities of radiation necessary to satisfactorily set these u.v. sealants are recommended.

Acoustics↗
PubMed1979

Caries prevalence and oral contraception.

A pilot study to determine whether 452 regular oral contraceptive users had a higher caries prevalence than 114 women not using those preparations found no significant variation between groups. Thus assumptions drawn from previous rodent studies do not justify the initiation of more complex laboratory-based human investigations.

Adult↗
PubMed1978

Progeston therapy for menstrually related aphthae.

Ten female patients with a history of recurrent aphthous lesions for at least 5 years with the lesions occurring regularly in the latter half at the menstrual cycle were treated with progestogen in the form of an intramuscular depot injection. Medroxyprogesterone acetate and gestronol hexanoate was used. All 10 patients were satisfied with the treatment; the side effects were few.

Adult↗
PubMed1978

Microhardness studies on the setting characteristics of fissure sealants.

The hardness of five fissure sealants was measured using a Wallace Microhardness Tester and found to continue to increase long after the initial setting. The effect of the intensity of radiation and exposure time on the setting of two u.v. activated sealants (Nuva-seal and Alphaseal) was also investigated, with higher intensities producing both a more rapid set and greater final hardness. Alphaseal required longer exposure at a given intensity of u.v. radiation to achieve the same hardness as Nuva-seal, and displayed relatively slow setting in depth, which could give rise to incomplete polymerization during clinical use, resulting in early sealant loss. Thus special care must be taken to ensure that Alphaseal receives an adequate exposure to u.v. radiation, and sources which are suitable for setting Nuva-seal may not be sufficiently powerful when applying Alphaseal.

Acrylates↗
PubMed1978

Ultra-violet absorption by two ultra-violet activated sealants.

Since the ability of u.v. setting pit and fissure sealants to set in depth is dependent on the penetration of the u.v. radiation, the absorption coefficients of Nuva-seal and Alphaseal were determined at 365 nm, the wavelength of radiation used to polymerise both materials. Nuva-seal and Alphaseal had absorption coefficients of 0.165 mm-1 and 6.25 mm-1, respectively. The u.v. fluorescent dye present in Alphaseal contributed 2.5 mm-1 to its absorption coefficient and the remaining absorption was due to the 5% w/w catalyst concentration present, since the basic resin had no significant absorption. Therefore Nuva-seal may set adequately to the depths required of fissure sealants, but Alphaseal may not, unless a very high intensity u.v. source is used. A reduction in the catalyst concentration and the removal of the u.v. fluorescent dye might improve the setting characteristics of Alphaseal.

Adsorption↗
PubMed1978

Five years of community preventive dentistry and health education in the county of Sutherland, Scotland.

Examination of 11-year-old Scots children who had participated in a 5-year, fortnightly dental health education and preventive dentistry programme showed that, compared with a similar age-matched group, the regimen produced mean DMF and DMFS reductions of 48.6% and 42.1%, respectively. In addition, the plaque and gingival indices differed significantly and 22.5% of test children were caries-free compared with only 7.6% of controls.

Child↗