The influence of a smear layer on the adhesion of sealer cements to dentin was assessed in recently extracted human anterior teeth. A total of 120 samples was tested, 40 per sealer; 20 each with and without the smear layer. The teeth were split longitudinally, and the internal surfaces were ground flat. One-half of each tooth was left with the smear layer intact, while the other half had the smear removed by washing for 3 min with 17% EDTA followed by 5.25% NaOCI. Evidence of the ability to remove the smear layer was verified by scanning electron microscopy. Using a specially designed jig, the sealer was placed into a 4-mm wide x 4 mm deep well which was then set onto the tooth.

Adhesiveness↗

PubMedDate not supplied

Cytotoxicity of glutaraldehyde and formaldehyde in relation to time of exposure and concentration.

The interacting effects of time of exposure and concentration as factors in cytotoxicity were compared for glutaraldehyde and formaldehyde. Cells from a human fibroblast cell line (WI-38) grown to confluence in 24-well trays were exposed to a range of concentrations of each agent, for periods of 4 to 24 hr. Cytotoxicity was measured by its effects on mitochondrial dehydrogenase activity, as assayed biochemically. Cytotoxic effects of formaldehyde occurred over a narrow concentration range from nontoxic to maximally toxic, and the range was little affected by time of exposure. In contrast, glutaraldehyde exerted its effect over a wider concentration range, and longer exposure times were necessary for maximal toxicity. The data suggest that long contact times of glutaraldehyde with dental pulp are necessary for maximum fixation. While 19% formaldehyde appeared to be more toxic than 2.5% glutaraldehyde in terms of serial dilution, little difference in cytotoxicity was observed when the data were calculated in terms of molar concentrations of the two agents.

Cell Line↗

PubMedDate not supplied

A critical look at glutaraldehyde.

Glutaraldehyde has been proposed as an alternative to formocresol in pulpotomy treatment of primary teeth. Data regarding effects of the two medicaments have been discussed in the literature, but little attention has been given to critical comparisons concerning parameters of toxicity, mutagenicity, and systemic distribution of the two agents. This paper reviews previous data on systemic distribution of glutaraldehyde and formocresol from pulpotomy sites, as well as cytotoxicity and mutagenicity of the agents. Comparisons reveal little difference between the agents on the parameters reviewed. The authors question the rationale for glutaraldehyde as an alternative to formocresol.

Formocresols↗

PubMedDate not supplied

Influence of pH on intestinal fluoride transport in vitro.

The effect of pH on intestinal fluoride (F) absorption was investigated in vitro using isolated segments of dog jejunum in a 2-chamber system. The pH of the mucosal buffer was varied in the range 6.5-8.2, and F concentration in the range 0.11-1.1 mM (2.1-21 ppm F). The serosal buffer was held constant at pH 7.5. No effect of pH within this physiological range was observed on F transport across the intestinal segment. Much lower pH values on the mucosal side inhibited F transport, but this appeared to be secondary to toxic effects on the epithelium, including an inhibition of water transport. Within the range tested, no evidence was found supporting the concept that F transport across intestinal epithelium occurs as the undissociated hydrogen fluoride (HF).

Analysis of Variance↗

PubMedDate not supplied