Allergy caused by latex proteins has been well documented. Thus, the study of non-latex materials, is necessary. The aim of this study is to evaluate the cytotoxicity of silver-coloured orthodontic chain elastics, of polyurethane and latex-free. Nine chain elastics from different manufactures (3 latex-free and 6 polyurethane) were divided into 9 groups of 10 elastics each: Group UK (Latex-free, 3M Unitek), Group TP (Látex-free, TP Orthodontics), Group AO (Látex-free, American Orthodontics), Group O (Polyurethane, OrthoSource), Group M (Polyurethane, Morelli), Group TD (Polyurethane, Tecnident), Group UD (Polyurethane, Uniden), Group AZ (Polyurethane, Abzil) and Group AK (Polyurethane, Aditek). The cytotoxicity essay was performed using cell cultures (L-929 line cells, mouse fibroblast) that were submitted to the cell viability test with neutral red ("dye-uptake") at 1, 2, 3, 7 and 28 days. Analysis of variance (ANOVA) with multiple comparisons and Tukey's test were employed (p<.05). The results showed no statistically significant differences between Groups UK, TP and AO in all experimental times (p>.05), except between the Groups UK and TP at 28 days (p<.05). There was significant statistically difference (p<.05) between the viability of the cells in the Groups O and TD with the Groups M, AZ, AK at 1 and 2 days. The polyurethane elastics showed lower cell viability in the first 48 hours, with increase on 3rd and 7th day, and viability similar to latex-free elastics at 28 days. It can be concluded that the latex-free chain elastic showed higher cell viability. The OrthoSource and Tecnident trademark showed lower cell viability the initial 48 hours.

O objetivo do presente trabalho é avaliar a citotoxicidade de quatro diferentes marcas comerciais de elásticos inter-maxilares intra-orais. Foram avaliados elásticos da American Orthodontics (Grupo 1), 3M Unitek (Grupo 2), Morelli (Grupo3) e Uniden (Grupo 4). Os elásticos foram previamente esterilizados em luz ultravioleta e colocados em placas de Petri, as quais continham cultura de células HEp-2., Após 24 h, as monocamadas de células foram coradas e, em seguida, realizada uma avaliação dos halos de difusão e de lise celular. Os resultados demonstraram a ausência de citotoxicidade nos elásticos da marca American Orthodontic e 3M Unitek e alta citotoxicidade nos elásticos das marcas Morelli e Uniden. Com base nos resultados encontrados, através da metodologia utilizada, conclui-se que os elásticos da marca Morelli e Uniden são citotóxicos.

The objective of the present study is to evaluate the cytotoxicity of four different commercial brands of intermaxillary orthodontic elastics. Four commercial brands of elastics were evaluated: American Orthodontics (Group1), 3M Unitek (Group 2), Morelli (Group 3) and Uniden (Group 4).The elastics were previously sterilized with Ultraviolet light and placed in Petri dish which tissue culture HEp-2. After 24 hr, the monolayers of cells were ruddystained with violet crystal and followed by an evaluation of the diffusion halo and cells lyses. The results demonstrated no cytotoxity for the American Orthodontic and the 3M Unitek elastics, and hight cytotoxicity for Morelli and Uniden elastics. Based on the results found, supported by the methodology utilized, it was concluded that the Morelli and Uniden elastics present high cytotoxicity.