Viability of fibroblasts in cell culture after treatment with different chemical retraction agents

Abstract

Prior to fixed prosthodontic impression procedures, temporary horizontal retraction of the free gingival tissue should be accomplished apically to the preparation finishing line. The mechanical-chemical method using cotton retraction cords of various sizes impregnated with various retraction chemicals is the most commonly employed retraction technique. Most retraction agents have pH values from 0.8 to 0.3, and are therefore hazardous to the cut dentine and periodontal tissues. Sympathomimetic vasoconstrictors introduced recently have a pH of 5.6, and are free of systemic side-effects. The present study using the dye exclusion test, colony forming ability test and colorimetric assay was undertaken to evaluate cytotoxic effects of four chemical retraction agents on cultured V-79 fibroblasts, and the dependence of cytotoxicity on the agent concentration and time of exposure. Original concentrations of retraction agents produced stronger cytotoxic effects than dilutions of 1:1 and 1:10. The most aggressive agent, 25% aluminium chloride, took only 1 min to damage all cell cultures. The proportion of cells damaged after 10 min of exposure to tetrahydrozoline was 60%, which was significantly less compared with other chemicals tested. With the colony forming ability test using retraction agents diluted to 1:10 the greatest number of colonies emerged in samples treated with tetrahydrozoline (statistical significance: P < 0.01). The colorimetric assay showed equal cytotoxic effects for 25% aluminium sulphate and tetrahydrozoline. The colorimetric test used in the study has proved an ergonomic, accurate and reliable test for cytotoxicity determination.

Chemical recycling of PET flakes into yarn

“…A similar effect was shown in case of Zn when AC8h × 36 were used (not shown). Cytotoxic effects of Al ions have been previously reported 51–54. However, to the best of our knowledge, possible synergistic effect of some combinations of the ions released by aluminum–bronze has not been analyzed.…”

Corrosion of dental nickel–aluminum bronze with a minor gold content‐mechanism and biological impact

“…Copper, aluminum, nickel, iron, zinc, and manganese were found after extraction of the alloy in acidic saline solution. All these elements are found to elicit toxic effects on cultured cells 26–29. Sjögren et al7 related the cytotoxocity of the alloy extracts used in their study to the content of zinc and Copper ions have been found to give a dose‐related cytotoxicity in the MTT assay 30.…”

A double‐blind randomised clinical trial of two techniques for gingival displacement

“…Astringents have only local action, which is an advantage because the systemic actions of adrenergic vasoconstrictors limit their clinical indications . Astringents have shown good clinical results , although some in vivo and in vitro studies have demonstrated that these products can induce undesirable effects in tissues of the gingival margin, mainly due to their low pH (1–3) .…”