[Biochemical study on the application of alpha-cyanoacrylate instant adhesives in dentistry]

The author biochemically evaluated the possible application of 4 types of alpha-cyanoacrylate adhesive agents (methyl, ethyl, isopropyl and isobutyl) in dentistry. A semiconductor temperature sensor was used to measure alpha-cyanoacrylate polymerization-temperature maximum heat, and an oscilloscope was employed to measure heat value. Amounts of formaldehyde eluted from the soluble component of alpha-cyanoacrylate was measured colorimetrically. In addition, to evaluate the effects of alpha-cyanoacrylate on pulp tissue, the soluble component of alpha-cyanoacrylate polymer was added to mouse macrophages. Changes in the numbers and morphology of macrophages and their glucose consumption in the supernatant medium were studied and compared with corresponding data obtained when formaldehyde alone was used. (1) During the polymerization of alpha-cyanoacrylate, when a glass fiber disc filter was used, the temperature increased by 19.1 degrees C in 1 microliter with methyl and by 8.6 degrees C with isobutyl. Even with the same alkyl, however, polymerization heat differed depending on the structure and constitution of the adhesive material and varied widely according to experimental conditions. (2) A mean maximum temperature of 1.7 degrees C in the dentin floor during polymerization of 10 microliters of alpha-cyanoacrylate monomer with methyl suggests no thermal injury to the pulp. (3) Formaldehyde was detected in all 4 adhesives when alpha-cyanoacrylate was dropped into distilled water for polymerization. Since, with each alkyl, the amount of eluted formaldehyde reached a maximum after 1 day of immersion, continuous elution of formaldehyde by hydrolysis was negligible. (4) A greater amount of formaldehyde was eluted from the polymer with methyl and ethyl, which have less Cs, than from the polymer with isopropyl and isobutyl, which have more Cs. These findings suggest that alkyl type affects the amount of eluted formaldehyde. (5) The soluble component of the alpha-cyanoacrylate polymer, either methyl or ethyl, had no effect on the number or morphology of mouse macrophages, as compared with corresponding data obtained when sterilized distilled water was used as a control. Isopropyl and isobutyl, however, decreased cell count and inhibited the extension of the sell soma. (6) The effects of isopropyl and isobutyl on the numbers and morphology of macrophages were similar to those of formaldehyde used alone at a concentration of 8 ppm or more. These findings suggest that, under the present experimental conditions, the above-mentioned changes in macrophages are the effects of about 8 ppm of formaldehyde. (7) The rate of glucose consumption by macrophages with methyl or ethyl was as high as that with the control.(ABSTRACT TRUNCATED AT 400 WORDS)