Search PubMed⌕ Search

Biomedical subjects

C Main

Publications and source records attributed to C Main.

31 records · Page 2Linked to original sources
PubMed1981

The effect of salivary contamination on fissure sealant--enamel bond strength.

The effect of accidental salivary contamination on the retention of fissure sealants is investigated via in vitro bond tests and scanning electron microscopy. The strength of the bond between sealant and saliva contaminated and washed enamel (168 +/- 14 kg cm-2) is not found to be significantly different from the bond strength to uncontaminated enamel (174 +/- kg cm-2). Unwashed contaminated enamel gives significantly reduced bond strength (68 +/- 11 kg cm-2).

Dental Bonding↗
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↗
PubMed1978

Antinuclear antibodies in patients receiving non-practolol beta-blockers.

Antinuclear antibodies (ANA) were found in 54 (7.0%) out of 767 treated hypertensive patients compared with 59 (2.4%) out of 2470 healthy controls. Inclusion of a non-practolol beta-blocker in the treatment regimen did not significantly affect the incidence of ANA. ANA was found in significantly more patients being treated with methyldopa (13.0%) than patients receiving other hypotensive agents (3.8%). Non-practolol beta-blockers in combination with methyldopa did not increase the incidence of ANA further.

Adrenergic beta-Antagonists↗
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↗