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.