Citotoxicity of orthodontic mini-implants / Citotoxidade de mini-implantes ortodônticos

ABSTRACT

OBJECTIVE: Based in the premise that Ti-6Al-4V orthodontic mini-implants can release metal ions into the body fluids, this research is aimed assess the cytotoxic effect of orthodontic mini-implant on L929 fibroblast cells. MATERIAL AND METHODS: Eighteen orthodontic mini-implants made of Ti-6Al-4V alloy were divided into 6 groups 1 (golden colour, SIN), 2 (silver colour, SIN), 3 (Neodent™), 4 (INP™), 5 (Mondeal™), and 6 (Titanium Fix™). The mini-implants were immersed into Eagle’s minimum essential medium for 24 hours, where supernatant removal and contact with L929 fibroblasts were performed. Cytotoxicity was evaluated in four different periods of time 24, 48, 72, and 168 hours. After being in contact with the mini-implants immersed, the cells were incubated for further 24 hours and then 100 ml of 0.01% neutral-red staining solution were added. After this period of time, they were fixed and a spectrophotometer was used for counting the viable cells. RESULTS: After the 24 hours period, statistical differences were found by comparing groups 1 and 2 to groups 3,4,5, and C+ (p < 0.05). After the 48 hours period, groups 1 and 2 were shown to be statistically different in relation to groups 3, 4, and C+. After the 72 hours period, statistical differences were found only in group 1 compared to groups 4, 5, 6, CC, and C+ (p < 0.05). After 7 days, no statistical differences were found between the mini-implants. CONCLUSION: Although mini-implants are made of the same alloy, there are differences in their cytotoxicity because of the different concentrations of chemical elements used for manufacturing them.

RESUMO

OBJETIVO: Baseando-se na premissa de que mini-implantes ortodônticos podem liberar íons metálicos nos fluidos corporais, pesquisou-se o efeito citotóxico de mini-implantes ortodônticos em fibroblastos L929. MATERIAL E MÉTODO: Dezoito mini-implantes ortodônticos confeccionados em liga Ti-6Al-4V foram divididos em seis grupos 1 (dourados, SIN), 2 (prateados SIN), 3 (Neodent), 4 (INP), 5 (Mondeal) e 6 (Titanium Fix). Os mini-implantes foram imersos em meio mínimo essencial Eagle por 24 horas, onde efetuou-se remoção do supernadante e contato com fibroblastos L929. A citotoxicidade foi avaliada em 4 diferentes tempos 24, 48, 72 e 168 horas. Após contato com os mini-implantes imersos, as células foram incubadas por mais 24 horas; então, 100 ml de solução corante neutra-vermelha foram adicionados. Após, foram fixadas e um espectrofotômetro foi usado para contar as células viáveis. RESULTADOS: Após o período de 23 horas, compararam-se os grupos 1 e 2 aos grupos 3, 4, 5 e C+. Após 72 horas, diferenças estatísticas foram encontradas somente no grupo 1, comparado aos grupos 4, 5, 6, CC e C+ (p < 0,05). Após 7 dias, não foram encontradas diferenças estatisticamente significantes entre os diversos mini-implantes.