Effects of DMAEMA and 4-methoxyphenol on gingival fibroblast growth, metabolism, and response to interleukin-1.

Abstract

Some components of resins used in restorative dentistry have been shown to alter metabolism in cultured oral epithelial cells. Here we have extended such studies to the underlying supportive tissue, composed of gingival fibroblasts (GF). Primary cultures of human GF were transferred to serum-free, defined medium and exposed to either 2-(dimethylamino)ethyl methacrylate (DMAEMA) or 4-methoxyphenol (MEHQ) for 24-72 h. At a DMAEMA concentration of 6.4 mM, which was well tolerated by epithelial cells, GF numbers, as estimated by crystal violet, and metabolic activity, as indicated by MTT, were reduced at least 60% within 24 h of exposure. Between 1.6 and 6.4 mM, there were dose-related reductions in cell numbers; however, at lower doses (0.32-0.64 mM), proliferation was stimulated. MEHQ, between 8 and 16 microM, did not stimulate cellular protein production. To examine the capacity of GF to respond to an inflammatory stimulus, interleukin-6 (IL-6) production by confluent cells was estimated without or with these compounds. DMAEMA (1.6- 6.4 mM) virtually eliminated the acute IL-6 response of these cells to an interleukin-1beta challenge; only at 0.32 mM DMAEMA was the response restored. MEHQ (1.6-16 microM) reduced the IL-6 response by >50%. In summary, both growth and the innate immune responsivity of GF were affected by DMAEMA and MEHQ in vitro; thus, these compounds deserve careful evaluation for biocompatibility.